Position indicator including conductor that surrounds conductive core body and is selectively electrically coupled to charging element of power supply circuit

ABSTRACT

A position indicator that electrostatically interacts with a sensor includes: a casing having a pen shape; a conductive core body including a pen tip that protrudes from an opening on one end in the axial direction of the casing; a conductor surrounding the core body; a signal transmitting circuit which, in operation, generates a signal that electrostatically interacts with the sensor, and supplies the generated signal to the core body; and a control circuit which, in operation, produces different electrostatic interactions with the sensor by performing a first control operation that sets the conductor in a state of being grounded while the signal is sent out from the pen tip of the core body to the sensor, and performing a second control operation that sets the conductor in a state different from the state of being grounded.

BACKGROUND Technical Field

The present disclosure relates to a capacitance type position indicatorused in conjunction with a position detecting device, and moreparticularly to detecting an inclination angle with respect to an inputsurface.

Background Art

There has conventionally been a position indicator of this kind thatenables detection of the inclination angle of a pen (inclination angleof the axial direction of a core body) with respect to the input surface(sensor surface) of a sensor of the position detecting device. Thedetected inclination angle is used to correct a cursor position on adisplay screen, which corresponds to the position of a pen tip of theposition indicator, to the pen tip position, irrespective of theinclination angle of the position indicator, and is used to operate anapplication according to the inclination angle.

As a method of detecting the inclination angle of a capacitance typeposition indicator, a method has conventionally been proposed whichdetects the inclination angle by detecting two signals on a sensor side,the two signals being a signal sent out from a core body (signalelectrode) to the sensor and a signal sent out from another signalelectrode disposed at a position separated in an axial direction from atip position of the core body with respect to the sensor surface (see,for example, Patent Document 1 (Japanese Patent Laid-Open No.2016-153954) and the like).

FIGS. 16A and 16B are diagrams of assistance in explaining aninclination angle detecting method disclosed in Patent Document 1. Aposition indicator of Patent Document 1 is provided with a core body 101sending out a signal for position detection and a tubular electrode 102disposed separately from the core body 101 so as to surround theperiphery of the core body 101 in the present example. In FIGS. 16A and16B, the tubular electrode 102 is illustrated in section. The core body101 penetrates a hollow portion of the tubular electrode 102, and thepen tip side of the core body 101 protrudes more to a sensor surface 103side than the tubular electrode 102.

The upper portion of FIG. 16A illustrates a state in which the axialdirection of the core body 101 of the position indicator isperpendicular to the sensor surface 103. At this time, a region in whicha signal from the core body 101 is detected at a predetermined signallevel or higher on the sensor surface 103 is a circular region 111illustrated in the middle portion of FIG. 16A, and a region in which asignal from the electrode 102 is detected at the predetermined level orhigher is a doughnut-shaped region 112 illustrated in the middle portionof FIG. 16A.

Hence, the reception levels of the signals from the position indicatorin the sensor as viewed in the horizontal axis (X-axis) direction of thesensor surface, for example, are as illustrated in the lower portion ofFIG. 16A. The level of the received signal from the core body 101 is amaximum, and the level of the received signal from the tubular electrode102 is detected on both sides of the maximum. At this time, a distancebetween an X-coordinate value X2 at which a peak value of the level ofthe received signal from the core body 101 is obtained, and a positionX1 at which a peak value of the level of the received signal from thetubular electrode 102 is obtained, and a distance between theX-coordinate value X2 and a position X3 are a same predetermineddistance. The same is true for Y-coordinates.

In addition, the upper portion of FIG. 16B illustrates a state in whichthe axial direction of the core body 101 of the position indicator isinclined at a predetermined inclination angle with respect to the sensorsurface. At this time, the region in which the signal from the core body101 is detected at the predetermined signal level or higher on thesensor surface 103 is an elliptical region 113 illustrated in the middleportion of FIG. 16B, and the region in which the signal from theelectrode 102 is detected at the predetermined signal level or higher isa deformed doughnut-shaped region 114 illustrated in the middle portionof FIG. 16B. At this time, relation between a distance between anX-coordinate value X5 at which a peak value of the level of the receivedsignal from the core body 101 is obtained, and an X-coordinate positionX4 at which a peak value of the level of the received signal from thetubular electrode 102 is obtained, and a distance between theX-coordinate value X5 and an X-coordinate position X6 is in accordancewith the inclination of the core body 101, as illustrated in the lowerportion of FIG. 16B. In addition, Y-coordinates are also in accordancewith the direction of the inclination and the inclination angle.

Hence, a position detecting device can detect the inclination angle ofthe core body 101 from the X-coordinates and the Y-coordinates.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent Laid-Open No. 2016-153954

BRIEF SUMMARY Technical Problems

According to the above-described conventional core body inclinationangle detecting method, signals need to be sent out from the twoelectrodes to the sensor. Thus, a configuration for supplying thesignals to the two electrodes becomes complex. In addition, when thetransmission signals are to be increased, the two electrodes may bedriven at the same time. However, driving two circuits increases powerconsumption.

It is an object of the present disclosure to provide a positionindicator that can solve the above problems.

Technical Solution

In order to solve the above problems, according to an embodiment of thepresent disclosure, there is provided a position that electrostaticallyinteracts with a sensor. The position indicator includes: a casinghaving a pen shape; a conductive core body including a pen tip thatprotrudes from an opening on one end in an axial direction of thecasing; a conductor surrounding the conductive core body; a signaltransmitting circuit which, in operation, generates a signal thatelectrostatically interacts with the sensor, and supplies the generatedsignal to the core body; and a control circuit which, in operation,produces different electrostatic interactions with the sensor byperforming a first control operation that sets the conductor surroundingthe core body in a state of being grounded while the signal is sent outfrom the pen tip of the core body to the sensor, and performing a secondcontrol operation that sets the conductor surrounding the core body in astate different from the state of being grounded.

In the position indicator having the above-described configuration,while the signal is supplied to the sensor through the core body, thefirst control operation that sets the conductor surrounding the corebody in the state of being grounded and the second control that sets theconductor in the state different from the state of being grounded areperformed with regard to the electric state of the conductor surroundingthe core body. That is, the position indicator sends out a signal fromone electrode, and controls the electric state of the other electrode.

In the sensor receiving the signal from the position indicator, thelevel of a received signal as the signal from the position indicator andthe detection region range of the received signal while the firstcontrol operation is performed, as well as the level of a receivedsignal as the signal from the position indicator and the detectionregion range of the received signal while the second control operationis performed, change according to the inclination angle of the corebody. Hence, a position detecting device can detect the inclinationangle of the core body by detecting information based on the level ofthe received signal as the signal from the position indicator and thedetection region range of the received signal while the first control isperformed, as well as the level of the received signal as the signalfrom the position indicator and the detection region range of thereceived signal while the second control is performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of assistance in explaining an example ofconstitution of a position indicator according to a first embodiment ofthe present disclosure.

FIG. 2 is a diagram of assistance in explaining an example ofconstitution of parts of the position indicator according to the firstembodiment of the present disclosure.

FIG. 3 is a diagram illustrating an example of a circuit configurationof a signal transmission control circuit of the position indicatoraccording to the first embodiment of the present disclosure.

FIGS. 4 A and 4B illustrate diagrams of assistance in explaining aninclination angle detecting method in the position indicator accordingto the first embodiment of the present disclosure.

FIG. 5 is a diagram illustrating an example of configuration of aposition detecting device used in conjunction with the positionindicator according to the first embodiment of the present disclosure.

FIG. 6 is a timing diagram of assistance in explaining a first exampleof a signal transmission control method in the position indicatoraccording to the first embodiment of the present disclosure.

FIG. 7 is a timing diagram of assistance in explaining a second exampleof the signal transmission control method in the position indicatoraccording to the first embodiment of the present disclosure.

FIGS. 8 A and 8B illustrate diagrams of assistance in explaining anexample of constitution of parts of a position indicator according to asecond embodiment of the present disclosure.

FIG. 9 is a diagram illustrating an example of constitution of a signaltransmission control circuit of the position indicator according to thesecond embodiment of the present disclosure.

FIG. 10 is a flowchart of assistance in explaining operation of parts ofthe position indicator according to the second embodiment of the presentdisclosure.

FIG. 11 is a diagram of assistance in explaining a modification of theposition indicator according to the second embodiment of the presentdisclosure.

FIGS. 12 A, 12B, and 12C illustrates diagrams of assistance inexplaining an example of constitution of parts of a position indicatoraccording to a third embodiment of the present disclosure.

FIG. 13 is a diagram illustrating an example of constitution of a signaltransmission control circuit of the position indicator according to thethird embodiment of the present disclosure.

FIG. 14 is a flowchart of assistance in explaining operation of parts ofthe position indicator according to the third embodiment of the presentdisclosure.

FIG. 15 is a timing diagram of assistance in explaining operation ofparts of the position indicator according to the third embodiment of thepresent disclosure.

FIGS. 16A and 16B illustrate diagrams of assistance in explaining aninclination angle detecting method of a conventional position indicator.

MODES FOR CARRYING OUT THE DISCLOSURE

Embodiments of a position indicator according to the present disclosurewill hereinafter be described with reference to the drawings.

FIRST EMBODIMENT

FIG. 1 is a diagram of assistance in explaining an example of aconfiguration of a position indicator 1 according to a first embodimentof the present disclosure, and is a partial longitudinal sectional viewof mainly a pen tip side. In the present embodiment, the positionindicator 1 is formed such that an external appearance of the positionindicator 1 has a pen shape.

[Description of Example of Structural Constitution of Position IndicatorAccording to First Embodiment]

The position indicator 1 according to the present embodiment has apen-shaped casing 2. The casing 2 is formed by a hollowcylindrical-shaped insulator portion 21 made of an insulating material,for example, a synthetic resin. In the present embodiment, at least apart of the outer circumferential surface of the insulator portion 21 ofthe casing 2, by which part an operator holds the position indicator 1,is covered by a conductor portion 22 formed of a metal, for example.

A printed circuit board 3, a battery 4 as a power supply circuit, and apen pressure detector 5 are arranged within the casing 2. Though notillustrated, the conductor portion 22 covering the outer circumferentialsurface of the casing 2 is electrically connected to a groundingconductor of the printed circuit board 3. Incidentally, the battery 4may be a dry cell, a rechargeable storage battery, or a power supplycircuit including a capacitor such as an electric double layer capacitorto be described later or the like.

As illustrated in FIG. 1, a signal transmission control circuit 30, aswell as other electronic parts and wiring patterns or the like notillustrated, is disposed on the printed circuit board 3. The signaltransmission control circuit 30 generates a signal for positiondetection and additional information, and sends out the generated signalfor position detection and the generated additional information from theposition indicator 1.

The battery 4 is a supply source of power to electronic circuits andelectronic parts formed on the printed circuit board 3. In FIG. 1, aterminal 42 is a terminal electrically connected to a power supplycircuit part on the printed circuit board 3. A positive side electrode41 of the battery 4 is in contact with the terminal 42 and electricallyconnected to the terminal 42. Though not illustrated, a negative sideelectrode of the battery 4 is set in pressing contact with a elasticallydisplaceable terminal directly connected to the grounding conductor ofthe printed circuit board 3 or connected to the grounding conductor ofthe printed circuit board 3 via the conductor portion 22 of the casing2.

As will be described later, in the present embodiment, the pen pressuredetector 5 has a configuration of a variable capacitance capacitor,exhibiting a capacitance according to a pen pressure applied to a corebody 6. Electrodes at both terminals of the variable capacitancecapacitor formed in the pen pressure detector 5 are connected to thesignal transmission control circuit 30 by a conductive pattern 31 c inFIG. 1.

An end portion of the core body 6, which end portion is on an oppositeside from a pen tip side projecting to the outside of the casing 2, isfitted into the pen pressure detector 5 disposed within a hollow portionof the casing 2. The core body 6 is thereby locked within the hollowportion of the casing 2 of the position indicator 1. Incidentally, thecore body 6 is configured to be released from the state of being fittedto the pen pressure detector 5 by being pulled out. That is, the corebody is replaceable for the position indicator 1.

The core body 6 is formed by a conductor, for example, a metal or a hardresin mixed with conductor powder. The core body 6 is electricallyconnected to the signal transmission control circuit 30 through aconductive pattern 31 a. The signal for position detection and theadditional information generated by the signal transmission controlcircuit 30 are sent out to a sensor of a position detecting devicethrough the core body 6 formed of the conductor.

In the present embodiment, an intermediate portion of the core body 6excluding the pen tip side of the core body 6 and the fitting side ofthe core body 6, which fitting side is fitted to the pen pressuredetector 5, is covered by a tubular shielding member 7. The shieldingmember 7 is formed by a conductor. The conductor of the shielding member7 is electrically connected to the signal transmission control circuit30 through a conductive pattern 31 b. As will be described later, theconductor of the shielding member 7 is switching-controlled by controlof the signal transmission control circuit 30 between two states, thatis, a state of being grounded in terms of alternating current and astate of floating in terms of potential.

In the state in which the conductor of the shielding member 7 isgrounded in terms of alternating current, the part covering the corebody 6 electrostatically shields the core body 6, and thus acts tosuppress (shield) the sending of a signal from the part covering thecore body 6. Hence, in the state in which the conductor of the shieldingmember 7 is grounded in terms of alternating current, a signal is sentout to the sensor mainly from only the pen tip side of the core body 6.On the other hand, when the conductor of the shielding member 7 is in afloating state in terms of potential, or when the conductor of theshielding member 7 is electrically connected to the core body 6, theelectrostatic shielding of the shielding member 7 is released, and asignal is sent out from the whole of the core body 6 to the sensor.

FIG. 2 is a diagram illustrating an example of detailed constitution ofpart of the core body 6, the shielding member 7, and the pen pressuredetector 5. FIG. 2 illustrates a sectional view of the part of the corebody 6, the shielding member 7, and the pen pressure detector 5.

As illustrated in FIG. 2, the core body 6 includes a core body main bodyportion 61 made of a conductive material, for example, a metal, andformed with a diameter of 1.9 mm, for example. In the presentembodiment, about half on the pen tip side of the core body main bodyportion 61 is covered by a protective member 62 made of an insulativematerial. The protective member 62 has a role of preventing damage tothe sensor input surface of the position detecting device and increasingan area of contact with the sensor input surface, and has a role ofmaking insulation from a tubular conductor 71 of the shielding member 7more secure.

As illustrated in FIG. 2, the shielding member 7 in the presentembodiment has a constitution in which an insulating layer 72 coverssubstantially the entire surface of the tubular conductor 71 formed by aconductive material, the entire surface including the outer wall surfaceand inner wall surface of the tubular conductor 71.

The pen pressure detector 5 has a constitution of a variable capacitancecapacitor that receives a pen pressure applied to the core body 6through a pressure transmitting member 8, and has a variablecapacitance. The pen pressure detector 5 in the present example uses penpressure detection means having a well-known constitution described inPatent Document: Japanese Patent Laid-Open No. 2011-186803, for example,and constitutes a variable capacitance capacitor whose capacitancechanges according to the pen pressure applied to the core body 6.

As illustrated in FIG. 2, the pen pressure detector 5 in the presentexample is formed by housing a plurality of parts, that is, a dielectric52, a conductive member 53, an elastic member 54, a slide member 55, anda terminal member 56 within a housing member 51 made of an insulativematerial, for example, a resin. The terminal member 56 constitutes afirst electrode of the variable capacitance capacitor formed by the penpressure detector 5. In addition, the conductive member 53 and theelastic member 54 are electrically connected to each other to form asecond electrode of the variable capacitance capacitor.

The slide member 55 is housed within the hollow portion of the housingmember 51 so as to be movable in an axial direction. However, the slidemember 55 is elastically biased to the pen tip side by the elasticmember 54 at all times.

The pressure transmitting member 8 is fitted into a fitting recessedportion 55 a of the slide member 55. The pressure transmitting member 8includes a core body fitting portion 81 into which an end portion 61 aof the core body main body portion 61 of the core body 6 is fitted, anda projecting portion 82 fitted into the slide member 55 of the penpressure detector 5.

In addition, a fitting recessed portion 51 a into which the shieldingmember 7 is fitted is formed at an end portion on the pen tip side ofthe housing member 51. An end portion of the shielding member 7, whichend portion is on an opposite side from the pen tip side of theshielding member 7, is fitted into the fitting recessed portion 51 a ofthe housing member 51. The shielding member 7 is thereby retained by thehousing member 51. As illustrated in FIG. 2, the core body 6 is insertedthrough the inside of the hollow portion of the tubular conductor 71 ofthe shielding member 7, and the end portion 61 a of the core body mainbody portion 61 is fitted into the core body fitting portion 81 of thepressure transmitting member 8.

The core body fitting portion 81 of the pressure transmitting member 8is provided with a recessed portion 81 a into which the end portion 61 aof the core body main body portion 61 of the core body 6 is inserted,the end portion 61 a being on an opposite side from the pen tip side ofthe core body main body portion 61. As illustrated in FIG. 2, providedwithin the recessed portion 81 a of the pressure transmitting member 8is a terminal piece 83 for making an electric connection between the endportion 61 a of the core body main body portion 61 of the core body 6,and the signal transmission control circuit 30 on the printed circuitboard 3. The terminal piece 83 is configured to elastically sandwich theend portion 61 a of the core body main body portion 61 of the core body6.

The core body main body portion 61 of the core body 6 is coupled to thepressure transmitting member 8 by inserting (press-fitting) the endportion 61 a of the core body main body portion 61 of the core body 6into the terminal piece 83, within the recessed portion 81 a of the corebody fitting portion 81 of the pressure transmitting member 8. The penpressure applied to the core body 6 is transmitted to the pen pressuredetector 5 to be described later via the pressure transmitting member 8.However, when the core body 6 is pulled with a predetermined force, thecore body 6 can be decoupled and pulled out from the pressuretransmitting member 8. That is, the core body 6 is replaceable.

An extension 83 a is extended out from the terminal piece 83 within therecessed portion 81 a of the pressure transmitting member 8. Theextension 83 a is connected to a lead electrode 84, which is connectedto a conductor pattern connected to the signal transmission controlcircuit 30 on the printed circuit board 3. A signal from the signaltransmission control circuit 30 on the printed circuit board 3 isthereby supplied to the core body main body portion 61 of the core body6.

In addition, as illustrated in FIG. 2, a terminal portion 73, in which apart of the insulating layer 72 of the shielding member 7 is peeled offand the surface of the tubular conductor 71 is thus exposed, and thesignal transmission control circuit 30 on the printed circuit board 3are electrically connected to each other through a gold wire 74 (and theconductive pattern 31 c), for example. The shielding member 7 is therebycontrolled by the signal transmission control circuit 30.

In the constitution of FIG. 2, when a pen pressure is applied to thecore body 6, the pen pressure is transmitted to the slide member 55 ofthe pen pressure detector 5 via the pressure transmitting member 8, andthe slide member 55 moves the conductive member 53 to the dielectric 52side against the elastic force of the elastic member 54 according to theapplied pen pressure. Then, an area of contact between the conductivemember 53 and the dielectric 52 changes according to the applied penpressure, and the capacitance of the variable capacitance capacitorformed between the first electrode and the second electrode is variedaccording to the applied pen pressure.

[Description of Example of Constitution of Signal Transmission ControlCircuit 30 of Position Indicator 1 According to First Embodiment]

FIG. 3 is a circuit configuration diagram of the signal transmissioncontrol circuit 30 of the position indicator 1 according to the presentembodiment. Specifically, the signal transmission control circuit 30 inthe present example includes a controller 301, an oscillating circuit302, and a switch circuit 303.

The controller 301 is constituted by a microprocessor, for example. Thecontroller 301 forms a control circuit that controls processingoperation as described later in the signal transmission control circuit30 of the position indicator 1. The controller 301 is supplied with apower supply voltage VDD from the battery 4 as an example of a drivingpower supply. The controller 301 controls the oscillating circuit 302,and switching-controls the switch circuit 303. The power supply voltageVDD from the battery 4 is supplied as power supply voltage for thesignal transmission control circuit 30 and other circuits via a powerswitch Psw. Though not illustrated in FIG. 1, the power switch Psw isturned on and off by pressing of an operating element provided on theside surface of the casing 2.

The controller 301 is also connected with a variable capacitancecapacitor 5C formed by the pen pressure detector 5. The controller 301detects a pen pressure applied to the core body 6 of the positionindicator 1 by monitoring the capacitance of the variable capacitancecapacitor 5C. Specifically, in the present embodiment, a dischargingresistor Rd is connected to the variable capacitance capacitor 5C, andthe controller 301 detects the capacitance of the variable capacitancecapacitor 5C by measuring a discharge time taken for the variablecapacitance capacitor 5C to reach a predetermined voltage across thevariable capacitance capacitor 5C from a state in which the variablecapacitance capacitor 5C is fully charged. The controller 301 detectsthe pen pressure from the detected capacitance.

The oscillating circuit 302 generates an alternating-current signal of afrequency f1=1.8 MHz, for example. The oscillating circuit 302 issupplied with the power supply voltage VDD from the battery 4 via thepower switch Psw. A continuous wave of a predetermined duration of thealternating-current signal from the oscillating circuit 302, that is, aburst signal, becomes a signal for position detection, which signal issent out to the sensor.

The controller 301 performs on-off control of the oscillating circuit302 by supplying a control signal (enable signal CT) to an enableterminal EN of the oscillating circuit 302. The controller 301 therebymakes the burst signal and an ASK (Amplitude Shift Keying) modulatedsignal generated from the oscillating circuit 302. The oscillatingcircuit 302 interrupts the generated alternating-current signalaccording to the enable signal CT from the controller 301. Theoscillating circuit 302 can thereby generate the burst signal and theASK modulated signal. In the present embodiment, the controller 301converts the value of the pen pressure detected as described above intoa digital signal, and controls the oscillating circuit 302 according tothe digital signal. The controller 301 thereby outputs information onthe pen pressure value as the ASK modulated signal from the oscillatingcircuit 302.

The output terminal of the oscillating circuit 302 in the presentembodiment is connected to the conductive core body main body portion 61of the core body 6. The alternating-current signal from the oscillatingcircuit 302 is sent out to the sensor of the position detecting devicethrough the conductive core body main body portion 61 of the core body6.

The switch circuit 303 is switching-controlled by a switching controlsignal SW from the controller 301. A movable terminal a of the switchcircuit 303 is connected to the tubular conductor 71 of the shieldingmember 7. One fixed terminal b of the switch circuit 303 is a free end,and another fixed terminal c of the switch circuit 303 is grounded. Itsuffices for the other fixed terminal c of the switch circuit 303 to begrounded in terms of alternating current. Thus, the other fixed terminalc of the switch circuit 303 may be configured to be connected to aterminal from which the power supply voltage VDD of the battery 4 isobtained.

When the movable terminal a of the switch circuit 303 is switched to thefixed terminal c side by the switching control signal SW from thecontroller 301, the tubular conductor 71 of the shielding member 7 is ina grounded state. Thus, the core body main body portion 61 of the corebody 6, excluding the pen tip side and the fitting side fitted to thepen pressure detector 5, is electrostatically shielded by the tubularconductor 71 of the shielding member 7. A signal from the positionindicator 1 is therefore sent out mainly from the pen tip side of thecore body main body portion 61 of the core body 6.

In addition, when the movable terminal a of the switch circuit 303 isswitched to the fixed terminal b side by the switching control signal SWfrom the controller 301, the tubular conductor 71 of the shieldingmember 7 is in a state of floating in terms of potential. Thus, the corebody main body portion 61 of the core body 6 is not electrostaticallyshielded. A signal from the position indicator 1 is therefore sent outfrom substantially the whole of the core body main body portion 61 ofthe core body 6.

In the present embodiment, as described above, the state of sending outa signal from the position indicator 1 is changed by switching theswitch circuit 303 between the two states described above, andfurthermore the inclination angle of the position indicator 1 withrespect to a sensor surface is detected by utilizing a fact that thestate of receiving a signal from the position indicator 1 in the twostates changes on the sensor surface on the position detecting deviceside according to the inclination angle of the position indicator 1.

For example, when the axial direction of the core body 6 of the positionindicator 1 is perpendicular (90 degrees) to the sensor surface 200 ofthe position detecting device, as illustrated in the upper portion ofFIG. 4A, in the state in which the movable terminal a of the switchcircuit 303 is connected to the fixed terminal c and thus the core body6 is electrostatically shielded, a signal is sent out only fromsubstantially a tip portion of the core body main body portion 61 of thecore body 6. The sensor of the position detecting device thereforeobtains a received signal of relatively steep signal levels, whichsignal exhibits a peak value at a tip position P0 of the core body 6, asindicated by a curve LA in the lower portion of FIG. 4A.

In addition, in the state in which the axial direction of the core body6 of the position indicator 1 is perpendicular (90 degrees) to thesensor surface 200 of the position detecting device, as illustrated inthe upper portion of FIG. 4A, and in the state in which the movableterminal a of the switch circuit 303 is connected to the fixed terminalb and thus electrostatic shielding is cleared, a signal is sent out fromsubstantially the whole of the core body main body portion 61 of thecore body 6. The sensor of the position detecting device thereforeobtains a received signal of signal levels having a relatively broadstrength distribution, though the received signal exhibits a peak valueat the tip position P0 of the core body 6 as in the state in which themovable terminal a of the switch circuit 303 is connected to the fixedterminal c, as indicated by a curve LB in the lower portion of FIG. 4A.

On the other hand, when the axial direction of the core body 6 of theposition indicator 1 is inclined at an inclination angle θ with respectto the sensor surface 200 of the position detecting device asillustrated in the upper portion of FIG. 4B, for example, in the statein which the movable terminal a of the switch circuit 303 is connectedto the fixed terminal c and thus the core body 6 is electrostaticallyshielded, due to a signal sent out only from substantially the tipportion of the core body main body portion 61 of the core body 6, thesensor of the position detecting device obtains a received signal ofrelatively steep signal levels, which signal exhibits a peak value at aposition P1 slightly shifted from the tip position of the core body 6,as indicated by a curve LC in the lower portion of FIG. 4B.

In addition, in the state in which the axial direction of the core body6 of the position indicator 1 is inclined at the inclination angle θwith respect to the sensor surface 200 of the position detecting device,as illustrated in the upper portion of FIG. 4B, and in the state inwhich the movable terminal a of the switch circuit 303 is connected tothe fixed terminal b and thus electrostatic shielding is cleared, asignal is sent out from substantially the whole of the core body mainbody portion 61 of the core body 6. The sensor of the position detectingdevice therefore obtains a received signal of signal levels having arelatively broad strength distribution, the received signal exhibiting apeak value at a position P2 that differs according to the magnitude ofthe inclination angle θ in the state in which the movable terminal a ofthe switch circuit 303 is connected to the fixed terminal c, asindicated by a curve LD in the lower portion of FIG. 4B.

Incidentally, as illustrated in FIG. 3, the switch circuit 303 isprovided to produce the state in which the core body 6 iselectrostatically shielded by the tubular conductor 71 of the shieldingmember 7 and the state in which the core body 6 is not electrostaticallyshielded. Hence, as indicated by a dotted line in FIG. 3, aconfiguration may be adopted in which the output terminal of theoscillating circuit 302 is connected to the fixed terminal b of theswitch circuit 303.

From the above, the position detecting device can detect the inclinationangle of the axial direction of the core body 6 of the positionindicator 1 with respect to the sensor surface 200 by detecting receivedsignals in the two respective states, that is, the state in which thecore body 6 is electrostatically shielded by the shielding member 7 inthe position indicator 1 and the state in which the electrostaticshielding of the core body 6 by the shielding member 7 is cleared, anddetecting positions at which peak values of levels of the respectivereceived signals are exhibited.

Specifically, in the state in which the positions at which peak valuesof the received signals in the two states, respectively, are exhibitedcoincide with each other as described above, the position detectingdevice can detect that the inclination angle of the axial direction ofthe core body 6 of the position indicator 1 with respect to the sensorsurface 200 is 90 degrees. When the positions at which the peak valuesof the received signals in the two states, respectively, are exhibiteddo not coincide with each other, the inclination angle of the axialdirection of the core body 6 of the position indicator 1 with respect tothe sensor surface 200 can be detected from a distance between thepositions at which those two peak values are exhibited.

In addition, according to the position indicator 1 of the foregoingfirst embodiment, when signals such as a signal for position detection,additional information, and the like are sent out to the sensor in thestate in which the core body 6 is electrostatically shielded by theshielding member 7, the signals sent out by the core body 6 are notaffected even when the casing 2 of the position indicator 1 is held by ahand.

[Description of Example of Constitution of Position Detecting Device]

As illustrated in FIG. 5, a position detecting device 201 according tothe present embodiment is constituted of a sensor 202 constituting theposition detecting device 201 and a pen indication detecting circuit 203connected to the sensor 202.

Though a sectional view of the sensor 202 is omitted, the sensor 202 inthe example is formed by laminating a first conductor group 211, aninsulating layer (not illustrated), and a second conductor group 212 inorder from a lower layer side. The first conductor group 211 is, forexample, formed by arranging, in a Y-axis direction, a plurality offirst parallel conductors 211Y₁, 211Y₂, . . . , 211Y_(m) (m is aninteger of 1 or more) extending in a horizontal direction (X-axisdirection) so as to be separated from each other at predeterminedintervals.

In addition, the second conductor group 212 is formed by arranging, inthe X-axis direction, a plurality of second parallel conductors 212X₁,212X₂, . . . , 212X_(n) (n is an integer of 1 or more) extending in adirection intersecting the extending direction of the first conductors211Y₁, 211Y₂, . . . , 211Y_(m), or a vertical direction (Y-axisdirection) orthogonal to the extending direction of the first conductors211Y₁, 211Y₂, . . . , 211Y_(m) in the present example, so as to beseparated from each other at predetermined intervals.

The sensor 202 of the position detecting device 201 thus has aconfiguration for detecting a position indicated by the positionindicator 1, by using a sensor pattern formed by making the firstconductor group 211 and the second conductor group 212 intersect eachother.

Incidentally, in the following description, when each of the firstconductors 211Y₁, 211Y₂, . . . , 211Y_(m) does not need to bedistinguished, the conductor will be referred to as a first conductor211Y. Similarly, when each of the second conductors 212X₁, 212X₂, . . ., 212X_(n) does not need to be distinguished, the conductor will bereferred to as a second conductor 212X.

In the position detecting device 201 according to the presentembodiment, the sensor 202 includes a sensor surface (indication inputsurface) 200 having a size corresponding to the size of a display screenof an electronic apparatus such as, for example, a tablet typeinformation terminal or the like, and is formed by the first conductorgroup 211 and the second conductor group 212 having opticaltransparency.

Incidentally, the first conductor group 211 and the second conductorgroup 212 may be of a configuration in which each of the first conductorgroup 211 and the second conductor group 212 is disposed on the samesurface side of the sensor substrate, or may be of a configuration inwhich the first conductor group 211 is disposed on one surface side ofthe sensor substrate and the second conductor group 212 is disposed onanother surface side.

The pen indication detecting circuit 203 includes a selecting circuit221 as an input-output interface with the sensor 202, an amplifiercircuit 222, a band-pass filter 223, a detecting circuit 224, a sampleand hold circuit 225, an AD (Analog to Digital) converting circuit 226,and a control circuit 220.

The selecting circuit 221 selects one conductor from among each of thefirst conductor group 211 and the second conductor group 212 on thebasis of a control signal from the control circuit 220. The conductorsselected by the selecting circuit 221 are connected to the amplifiercircuit 222. A signal from the position indicator 1 is detected by theselected conductors, and amplified by the amplifier circuit 222. Theoutput of the amplifier circuit 222 is supplied to the band-pass filter223, so that only a component having the frequency of the signaltransmitted from the position indicator 1 is extracted.

The output signal of the band-pass filter 223 is detected by thedetecting circuit 224. The output signal of the detecting circuit 224 issupplied to the sample and hold circuit 225 to be sampled and held inpredetermined timing by a sampling signal from the control circuit 220,and thereafter converted into a digital value by the AD convertingcircuit 226. Digital data from the AD converting circuit 226 is read andprocessed by the control circuit 220.

The control circuit 220 operates so as to send out a control signal toeach of the sample and hold circuit 225, the AD converting circuit 226,and the selecting circuit 221 according to a program stored in aninternal ROM of the control circuit 220. In addition, the controlcircuit 220 calculates position coordinates on the sensor 202, whichposition coordinates are indicated by the position indicator 1, from thedigital data from the AD converting circuit 226, and outputs data on theposition coordinates to another processing processor or the like withinthe electronic apparatus such as, for example, a tablet type informationterminal or the like.

In addition, the control circuit 220 of the position detecting device201 detects, as signals from the position indicator 1, a signal in thestate in which the core body main body portion 61 of the core body 6 iselectrostatically shielded and a signal in the state in which theelectrostatic shielding of the core body main body portion 61 of thecore body 6 is cleared, as described above. Then, information based on adistance between positions at which peak values of the received signalsin those two detected states, respectively, are exhibited is detected,and the inclination angle of the core body 6 of the position indicator 1with respect to the sensor surface 200 is calculated on the basis of thedetected information on the distance.

In this case, the control circuit 220 of the position detecting device201 has a correspondence table of data on the distance between thepositions at which the peak values of the received signals in the twostates, respectively, are exhibited, and data on the inclination angleof the axial direction of the core body 6 of the position indicator 1with respect to the sensor surface 200. The control circuit 220 of theposition detecting device 201 detects information on the inclinationangle of the axial direction of the core body 6 of the positionindicator 1 with respect to the sensor surface 200 by detecting theinformation on the distance between the positions at which the peakvalues of the received signals in the two states, respectively, areexhibited, and by referring to the correspondence table.

Incidentally, it is needless to say that the control circuit 220 of theposition detecting device 201 may not have the correspondence table asdescribed above, but may calculate the information on the inclinationangle of the core body 6 of the position indicator 1 by calculation fromthe detected information on the distance between the positions at whichthe peak values of the received signals in the two states, respectively,are exhibited.

[Signal Transmission Control of Position Indicator 1 for DetectingInclination Angle of Axial Direction of Core Body 6]

In order to be able to detect the inclination angle of the axialdirection of the core body 6 of the position indicator 1 with respect tothe sensor surface as described with reference to FIG. 3 and FIGS. 4Aand 4B, the position detecting device 201 needs to detect in which ofthe two states a received signal from the position indicator 1 is, thetwo states being the state in which the core body 6 is electrostaticallyshielded by the shielding member 7 in the position indicator 1 and thestate in which the electrostatic shielding of the core body 6 by theshielding member 7 is cleared.

In the present embodiment, the position detecting device 201 detects inwhich of the two states the received signal is on the basis of thesignal from the position indicator 1. Therefore, in the presentembodiment, the controller 301 of the signal transmission controlcircuit 30 of the position indicator 1 performs control to transmit asignal such that the position detecting device 201 can perform thedetection.

First Example of Signal Transmission Control

A first example of a signal transmission control method performed by thecontroller 301 of the signal transmission control circuit 30 of theposition indicator 1 will be described with reference to FIG. 6.Incidentally, it is needless to say that the following signaltransmission control method is performed in a state in which the powerswitch Psw is on and thus the voltage of the battery 4 is supplied tothe oscillating circuit 302 and other circuits.

FIG. 6 is a timing diagram of assistance in explaining a first exampleof the signal transmission control method performed by the controller301. In the present example, the controller 301 performs enable controlof the oscillating circuit 302 by the enable signal CT (see portion (A)of FIG. 6), and thereby performs control so as to make a signal SBoutput from the oscillating circuit 302 as illustrated in portion (D) ofFIG. 6, which signal repeats, in cycles Ta, a signal constituted of asignal for position detection, which signal is formed by a burst signalhaving a predetermined time length, a start signal ST, shield stateinformation SH, and digital additional data such as pen pressure data orthe like, as illustrated in portions (B) and (C) of FIG. 6.

Specifically, the enable signal CT from the controller 301 maintains ahigh level during a predetermined period from a start of a cycle Ta, asillustrated in portion (A) of FIG. 6. In this predetermined period, asignal for position detection, which signal is formed by a burst signal,is output from the oscillating circuit 302, as illustrated in portions(B) and (C) of FIG. 6. This signal for position detection is transmittedto the sensor 202 of the position detecting device 201 through the corebody main body portion 61 of the core body 6.

The length of the transmission period of the signal for positiondetection is a time length in which the pen indication detecting circuit203 of the position detecting device 201 can detect a position indicatedon the sensor 202 by the position indicator 1. The length of thetransmission period of the signal for position detection is, forexample, a time length in which all of the first conductors 211Y and thesecond conductors 212X of the sensor 202 can be scanned once or more,preferably a plurality of times or more.

During the transmission period of the signal for position detection, thecontroller 301 of the position indicator 1 detects a pen pressureapplied to the core body 6 as a detection signal according to thecapacitance of the variable capacitance capacitor 5C formed by the penpressure detector 5, and obtains the pen pressure as a 10-bit value(binary code), for example, from the detection signal.

Then, as illustrated in portions (A) to (C) of FIG. 6, after thetransmission period of the signal for position detection is ended, thecontroller 301 of the signal transmission control circuit 30 of theposition indicator 1 sets a transmission period for additional data suchas pen pressure data or the like, and performs ASK modulation of thesignal output from the oscillating circuit 302 by controlling the enablesignal CT (portion (A) of FIG. 6) to a high level or a low level in apredetermined cycle td (td<Ta). The predetermined cycle td correspondsto a transmission interval for 1 bit of transmission data (digitaldata).

In this case, as illustrated in portions (A) and (B) of FIG. 6, whentransmission data (binary code) is “0,” the enable signal CT is set atthe low level and the oscillating signal from the oscillating circuit302 is not output. When the transmission data (binary code) is “1,” theenable signal CT is set at the high level as illustrated in portion (A)of FIG. 6 in a cycle td, and the oscillating signal from the oscillatingcircuit 302 is controlled to be sent out.

In a first cycle td of the transmission period of the additional data,the transmission data is always set to “1,” which is used as a startsignal ST of the transmission period of the additional data, asillustrated in portion (C) of FIG. 6. The start signal ST is a timingsignal for enabling data sending-out timing of the following additionalinformation to be accurately determined on the position detecting device201 side. Incidentally, in place of the start signal ST, an end timepoint of the signal for position detection can also be used as thetiming signal.

The controller 301 controls the enable signal CT (portion (A) of FIG. 6)supplied to the oscillating circuit 302 so as to send out the shieldstate information SH in a next cycle td following the start signal ST.The shield state information SH is information for notifying, to theposition detecting device side, timing of a state in which a signal issent out in the state in which electrostatic shielding of the core body6 by the shielding member 7 is performed, and a state in which a signalis sent out in the state in which the electrostatic shielding of thecore body 6 by the shielding member 7 is cleared.

In the example, the shield state information SH indicates whether thesending out of the signal, in a cycle T next to a cycle T in which theshield state information SH is included, is performed in the state inwhich the electrostatic shielding of the core body 6 by the shieldingmember 7 is performed or in the state in which the electrostaticshielding of the core body 6 by the shielding member 7 is cleared. Thecontroller 301 generates the switching control signal SW (see portion(E) of FIG. 6) so as to switch the switch circuit 303 in each cycle T incorrespondence with the shield state information SH.

Specifically, in the example of FIG. 6, in a cycle T next to a cycle Tin which the shield state information SH is “1,” the controller 301performs control so as to switch the switch circuit 303 to the fixedterminal b side by setting the switching control signal SW (see portion(E) of FIG. 6) to the low level, and thus sets the state in which theelectrostatic shielding of the core body main body portion 61 of thecore body 6 is cleared (shield-off state). In addition, in a cycle Tnext to a cycle T in which the shield state information SH is “0,” thecontroller 301 performs control so as to switch the switch circuit 303to the fixed terminal c side by setting the switching control signal SW(see portion (E) of FIG. 6) to the high level, and thus sets the statein which the electrostatic shielding of the core body main body portion61 of the core body 6 is performed (shield-on state).

Following the shield state information SH, the controller 301 controlsthe enable signal CT so as to sequentially transmit the pen pressuredata of 10 bits to the sensor 202 of the position detecting device 201.Portions (A) and (B) of FIG. 6 represent a case where the pen pressuredata to be transmitted is “0101110101.” Incidentally, following the penpressure data, the position indicator 1 may send out identificationinformation of the position indicator 1 itself and data on a batteryremaining capacity or the like as an ASK signal or an OOK (On OffKeying) signal as in the foregoing.

The oscillating circuit 302 of the signal transmission control circuit30 of the position indicator 1 repeatedly sends out the signal in thecycle Ta including the transmission period of the signal for positiondetection and the transmission period of the additional informationformed by digital data as described above, as illustrated in portion (D)of FIG. 6 on the basis of control of the controller 301. In addition,the controller 301 alternately switches the movable terminal a of theswitch circuit 303 to the fixed terminal b or the fixed terminal c ineach cycle Ta by the switching control signal SW (see portion (E) ofFIG. 6). The position indicator 1 thereby repeats, in each cycle Ta, thestate in which the core body main body portion 61 of the core body 6 iselectrostatically shielded by the shielding member 7 and the state inwhich the electrostatic shielding is cleared.

Incidentally, the controller 301 can detect whether or not a penpressure is applied to the core body 6 of the position indicator 1 bydetecting the capacitance of the variable capacitance capacitor 5Cformed by the pen pressure detector 5 as described above. That is, thecontroller 301 can detect whether or not the tip portion of the corebody 6 of the position indicator 1 has touched the sensor surface 200 ofthe sensor 202 of the position detecting device 201. Accordingly, in thepresent embodiment, when the controller 301 of the position indicator 1determines from the value of the capacitance of the variable capacitancecapacitor 5C that no pen pressure is applied to the core body 6, thecontroller 301 controls the oscillating circuit 302 so as not to sendout the signal for position detection nor the additional information, orso as to send out the signal for position detection but not to send outthe additional information, and does not perform switching control ofthe switch circuit 303 in each cycle Ta by performing control so as toconnect the movable terminal a of the switch circuit 303 to the fixedterminal c at all times.

When the controller 301 determines from the value of the capacitance ofthe variable capacitance capacitor 5C that a pen pressure is applied tothe core body 6, the controller 301 controls the oscillating circuit 302so as to send out the signal for position detection and the additionalinformation, and performs switching control of the switch circuit 303 byalternately switching the movable terminal a of the switch circuit 303to the fixed terminal b and the fixed terminal c in each cycle Ta.

Incidentally, without performing such control according to a result ofthe detection of the pen pressure, the controller 301 may of coursealways send out a signal as in portion (D) of FIG. 6 and perform thecontrol of switching the switch circuit 303 in each cycle Ta asillustrated in portion (E) of FIG. 6 while the power of the battery 4 ison.

The position detecting device receives the signal from the positionindicator 1 by the sensor 202, and performs reception processing asdescribed in the following.

In the pen indication detecting circuit 203 of the position detectingdevice 201, the control circuit 220, for example, first supplies aselecting signal for sequentially selecting the second conductors 212X₁to 212X_(n) to the selecting circuit 221, and reads, as a signal level,data output from the AD converting circuit 226 at a time of selection ofeach of the second conductors 212X₁ to 212X_(n). Then, when the signallevels of all of the second conductors 212X₁ to 212X_(n) do not reach apredetermined value, the control circuit 220 determines that theposition indicator 1 is not on the sensor 202, and repeats the controlof sequentially selecting the second conductors 212X₁ to 212X_(n).

When a signal having a level equal to or higher than the predeterminedvalue is detected from one of the second conductors 212X₁ to 212X_(n),the control circuit 220 stores the number of a second conductor 212Xfrom which a highest signal level (peak value; the same applieshereinafter) is detected, and a plurality of second conductors 212X inthe vicinity thereof. Then, the control circuit 220 sequentially selectsthe first conductors 211Y₁ to 211Y_(m) by controlling the selectingcircuit 221, and reads signal levels from the AD converting circuit 226.At this time, the control circuit 220 stores the numbers of a firstconductor 211Y from which a highest signal level is detected, and aplurality of first conductors 211Y in the vicinity thereof.

Then, the control circuit 220 detects a position on the sensor 202,which position is indicated by the position indicator 1 from the numberof the second conductor 212X from which the highest signal level isdetected, and the number of the first conductor 211Y from which thehighest signal level is detected, and the plurality of second conductors212X in the vicinity of the second conductor 212X from which the highestsignal level is detected, and the plurality of first conductors 211Y inthe vicinity of the first conductor 211Y from which the highest signallevel is detected, the numbers being stored as described above.

After the control circuit 220 selects a last first conductor 211Y_(m) bythe selecting circuit 221 and completes detecting a signal level, thecontrol circuit 220 waits for an end of the transmission period of thesignal for position detection from the position indicator 1. After thecontrol circuit 220 detects the start signal ST after an end of thetransmission period of the signal for position detection, the controlcircuit 220 performs an operation of reading data such as pen pressuredata or the like, and reconstructing a digital signal.

In addition, the control circuit 220 detects the shield stateinformation SH following the detection of the start signal ST, anddetermines whether the shield state information SH is “1” or “0.” On thebasis of a result of the determination, the control circuit 220 detectsa received signal in the state in which the core body 6 of the positionindicator 1 is electrostatically shielded and a received signal level inthe state in which the electrostatic shielding is cleared. The controlcircuit 220 detects the inclination angle of the core body 6 of theposition indicator 1 from the positions of peak values of both thereceived signals. The control circuit 220 then repeats the aboveoperation.

Incidentally, in the above first example, the additional information istransmitted also in the period of the state in which the switchingcontrol signal SW of the switch circuit 303 is set to the low level andthus the electrostatic shielding of the core body 6 is cleared. However,the additional information may not be transmitted in the period of thestate in which the electrostatic shielding of the core body 6 iscleared.

In addition, in the above first example, the controller 301 sets theentire period of one cycle Ta as the period of the state in which theswitching control signal SW of the switch circuit 303 is set at the lowlevel and thus the electrostatic shielding of the core body 6 iscleared, and alternately produces the state in which the electrostaticshielding is performed and the state in which the electrostaticshielding is cleared. However, as illustrated in portion (F) of FIG. 6,the electrostatic shielding of the core body 6 may be cleared by settingthe switching control signal SW of the switch circuit 303 at the lowlevel in correspondence with the transmission interval of the signal forposition detection, and the electrostatic shielding may be performed bysetting the switching control signal SW of the switch circuit 303 at thehigh level in correspondence with the transmission period of theadditional information. Consequently, during the transmission period ofthe additional information, the core body 6 is electrostaticallyshielded at all times, and therefore the transmission signal is sent outonly from the tip portion side of the core body 6. Thus, the positiondetecting device 201 can detect the additional information well withineach period Ta.

Incidentally, while the state of the electrostatic shielding of the corebody 6 in the transmission period after one cycle Ta is notified to theposition detecting device 201 by the shield state information SH in theabove-described first example, the state of the electrostatic shieldingof the core body 6 in an immediately preceding transmission period ofthe signal for position detection may be notified to the positiondetecting device 201 by the shield state information SH.

Second Example of Signal Transmission Control

A second example of the signal transmission control method performed bythe controller 301 of the signal transmission control circuit 30 of theposition indicator 1 will be described with reference to FIG. 7.

FIG. 7 is a timing diagram of assistance in explaining the secondexample of the signal transmission control method performed by thecontroller 301. In the above-described first example, the shield stateinformation SH is transmitted from the position indicator 1 to theposition detecting device 201 in order to notify the electrostaticshielding state. The second example is an example in which informationfor notifying the electrostatic shielding state such as the shield stateinformation SH in the first example does not need to be sent.

In the present example, the controller 301 performs enable control ofthe oscillating circuit 302 by the enable signal CT (see portion (A) ofFIG. 7), and thereby performs control so as to make a signal SB outputfrom the oscillating circuit 302 as illustrated in portion (D) of FIG.7, which signal repeats, in cycles Tb, a signal constituted of a signalfor position detection, which signal is formed by a burst signal havinga predetermined time length, a start signal ST, and digital additionaldata such as pen pressure data or the like, as illustrated in portions(B) and (C) of FIG. 7.

In the second example, as illustrated in portion (C) of FIG. 7, theshield state information SH is not included in the transmission periodof the additional information. Instead, in the second example, asillustrated in portions (A) to (C) of FIG. 7, the length of atransmission period Ps of a signal for position detection is, forexample, set to be twice the length of the first example. Then, asillustrated in portions (D) and (E) of FIG. 7, the transmission periodPs of the signal for position detection is divided into two parts, andcontrol is performed so as to perform the electrostatic shielding of thecore body 6 by the shielding member 7 in the first half period of Ps/2,and clear the electrostatic shielding of the core body 6 by theshielding member 7 in the second half period of Ps/2.

That is, as illustrated in portion (E) of FIG. 7, the controller 301generates a switching control signal SW that performs control so as toclear the electrostatic shielding of the core body 6 by the shieldingmember 7, by switching the movable terminal a of the switch circuit 303to the fixed terminal b in only the second half period of Ps/2 of thetransmission period of the signal for position detection within theperiod of each cycle Tb, and perform the electrostatic shielding of thecore body 6 by the shielding member 7 by switching the movable terminala to the fixed terminal c in other periods. The controller 301 suppliesthe switching control signal SW to the switch circuit 303. The otherconfiguration is similar to that of the first example.

In the second example, the control circuit 220 of the position detectingdevice 201 detects an end of the transmission period of the signal forposition detection or the start signal ST, and thereby detects a starttime point of the transmission period Ps of a next signal for positiondetection. Then, the control circuit 220 detects a signal in the statein which the electrostatic shield of the core body 6 by the shieldingmember 7 is performed as a received signal from the position indicator 1in the first half period of Ps/2 of the transmission period Ps of thesignal for position detection, and detects a signal in the state inwhich the electrostatic shielding of the core body 6 by the shieldingmember 7 is cleared as a received signal from the position indicator 1in the second half period of Ps/2. The control circuit 220 then detectsthe inclination angle of the core body 6 of the position indicator 1 asdescribed above from the signals received in those two periods.

Incidentally, in the example of FIG. 7, as illustrated in portion (E) ofFIG. 7, the core body 6 is electrostatically shielded by the shieldingmember 7 in the first half period of Ps/2 of the transmission period Psof the signal for position detection, and the electrostatic shielding ofthe core body 6 by the shielding member 7 is cleared in the second halfperiod of Ps/2. However, as illustrated in portion (F) of FIG. 7, bycontrol of the controller 301, the electrostatic shielding of the corebody 6 by the shielding member 7 may be performed in correspondence withthe transmission period Ps of the signal for position detection, and theelectrostatic shielding of the core body 6 by the shielding member 7 maybe cleared in correspondence with the transmission of the additionalinformation such as pen pressure data or the like following thetransmission of the signal for position detection.

SECOND EMBODIMENT

In the position indicator 1 according to the foregoing first embodiment,the shielding member 7 is formed by using a tubular conductor 71.However, the shielding member is not limited to such a tubularconductor. In a position indicator 1A according to a second embodimentto be described in the following, the shielding member is formed by acoil that houses a core body within a winding space of the coil. In theposition indicator 1A according to the second embodiment, the shieldingmember is formed by the coil, and the coil is used also as an inductioncoil for performing electromagnetic induction type charging. Hence, theposition indicator 1A according to the second embodiment does notinclude a battery, but instead includes a storage element, which is, forexample, a capacitor such as an electric double layer capacitor or thelike, a rechargeable storage battery, or the like.

In addition, in the first embodiment, information for enabling theposition detecting device side to recognize the state in which the corebody is electrostatically shielded by the shielding member in theposition indicator and the state in which the electrostatic shielding ofthe core body is cleared is notified from the position indicator to theposition detecting device side. On the other hand, in the secondembodiment, instead of transmitting the information for notifying thestate of electrostatic shielding of the core body from the positionindicator 1A to the position detecting device side, an inclination angledetection request signal transmitted from the position detecting deviceis received, and in response to the received inclination angle detectionrequest signal (hereinafter referred to simply as a request signal forshort), the position indicator 1A performs, in a predetermined sequence,signal transmission in the state in which the core body iselectrostatically shielded by the shielding member and signaltransmission in the state in which the electrostatic shielding of thecore body by the shielding member is cleared.

FIGS. 8 A and 8B are diagrams of assistance in explaining a core body 6Aand a shielding member 7A of the position indicator 1A according to thesecond embodiment. FIG. 8A is an exploded perspective view of the partof the core body 6A, the shielding member 7A, and a pen pressuredetector 5A. FIG. 8B is a fragmentary enlarged view of the pen tip sideof the position indicator 1A with a casing 2 illustrated in section. Inthe position indicator 1A to be described in the following, thereference numerals of parts corresponding to those of the positionindicator 1 according to the first embodiment are illustrated by addinga suffix A to the same numbers.

In the position indicator 1A according to the second embodiment, thecore body 6A, for example, has a constitution of a conductive metallicrod or a rod-shaped body made of a hard resin mixed with conductivepowder. The shielding member 7A is formed by winding a coil 75 formed bywinding a conductor around, for example, a cylindrical-shaped magneticcore, or a ferrite core 76 in the example. As illustrated in FIG. 8B, anend portion of the ferrite core 76, which end portion is on an oppositeside from a pen tip side in the axial direction of the ferrite core 76,is fitted into a fitting recessed portion 51Aa of a housing member 51Ainternally housing the pen pressure detector 5A.

A through hole 76 a penetrating in the axial direction is formed in theferrite core 76. The inside diameter r of the through hole 76 a isselected to be a value slightly larger than the outside diameter of thecore body 6A. The core body 6A is inserted through the through hole 76 aof the ferrite core 76. Then, as illustrated in FIG. 8B, an end portion6Ab of the core body 6A, which end portion is on an opposite side from atip portion 6Aa of the core body 6A, is fitted into the pen pressuredetector 5A provided within the housing member 51A.

In a state in which the core body 6A is fitted to the pen pressuredetector 5A, the tip portion 6Aa side of the core body 6A protrudes fromthe ferrite core 76. When a user applies a force so as to pull out thecore body 6A, the fitting between the core body 6A and a fitting portionof the pen pressure detector 5A is easily released, and the core body 6Acan be pulled out. That is, the core body 6A is replaceable. The penpressure detector 5A has a configuration similar to that of the penpressure detector 5 of the position indicator 1 according to theforegoing first embodiment.

In the present example, a printed circuit board 3A is attached withinthe housing member 51A. An electronic circuit formed on the printedcircuit board 3A is electrically connected to both terminals of avariable capacitance capacitor 5AC constituting the pen pressuredetector 5A, and one terminal 75 a and another terminal 75 b of the coil75 are also electrically connected to the electronic circuit on theprinted circuit board 3A.

As illustrated in FIG. 8B, the position indicator 1A according to thesecond embodiment has a conductor sleeve 23 at a pen tip portion of aninsulator portion 21A of a casing 2A, the conductor sleeve 23 beingprovided as a configuration for receiving an instruction signal from theposition detecting device. The conductor sleeve 23 has a tubularcap-like shape covering the pen tip portion of the insulator portion 21Aof the casing 2A. The conductor sleeve 23 is electrically insulated froma conductor portion (not illustrated in FIGS. 8A and 8B of the casing2A. The conductor sleeve 23 is capable of receiving a signal from thesensor of the position detecting device by electrostatic coupling.Though not illustrated, the conductor sleeve 23 is electricallyconnected to the electronic circuit on the printed circuit board 3A.

[Description of Example of Constitution of Signal Transmission ControlCircuit 30A of Position Indicator 1A According to Second Embodiment]

FIG. 9 is a diagram illustrating an example of constitution of a signaltransmission control circuit 30A of the position indicator 1A accordingto the second embodiment. The signal transmission control circuit 30A inthe present example includes a controller 301A, an oscillating circuit302A, a switch circuit 303A, a switch circuit 3044, a charging typepower supply circuit 304, and a received signal detecting circuit 305.

The controller 301A is formed by a microprocessor as with the controller301. The controller 301A constitutes a control circuit that controlsprocessing operation of the signal transmission control circuit 30A ofthe position indicator 1A. In the present example, a power supplyvoltage VDD from the power supply circuit 304 is supplied as a drivingpower to the controller 301A. The controller 301A controls theoscillating circuit 302A, and performs switching control of the switchcircuit 303A and the switch circuit 3044.

In addition, the controller 301A is connected with the variablecapacitance capacitor 5AC constituting the pen pressure detector 5A. Aswith the controller 301 in the first embodiment, the controller 301Adetects the capacitance of the variable capacitance capacitor 5AC bymeasuring a time taken for the variable capacitance capacitor 5AC toreach a predetermined voltage across the variable capacitance capacitor5AC by discharging through a resistor Rd from a fully charged state, anddetects a pen pressure from the detected capacitance.

As with the oscillating circuit 302, the oscillating circuit 302Agenerates an alternating-current signal of a frequency f1=1.8 MHz, forexample. The oscillating circuit 302A is supplied with the power supplyvoltage VDD from the power supply circuit 304 in the present example.

As in the case of the foregoing first embodiment, the controller 301Aperforms on-off control of the oscillating circuit 302A by supplying acontrol signal (enable signal CTA) to an enable terminal EN of theoscillating circuit 302A. The controller 301A thereby makes a burstsignal (signal for position detection) and an ASK modulated signal(additional information) generated from the oscillating circuit 302A,and stops the sending out of the signals.

An output terminal of the oscillating circuit 302A in the presentembodiment is connected to the conductive core body 6A. Thealternating-current signal from the oscillating circuit 302A is sent outto the sensor of the position detecting device through the core body 6A.

The switch circuit 303A is switching-controlled by a switching controlsignal SWA from the controller 301A. A movable terminal a of the switchcircuit 303A is connected to one terminal 75 a of the coil 75constituting the shielding member 7A. One fixed terminal b of the switchcircuit 303A is a free end, and another fixed terminal c of the switchcircuit 303A is grounded.

The other terminal 75 b of the coil 75 constituting the shielding member7A is connected to a movable terminal a of the switch circuit 3044switching-controlled by a switching control signal SWB from thecontroller 301A. One fixed terminal b of the switch circuit 3044 isconnected to the anode of a rectifying diode 3041. Another fixedterminal c of the switch circuit 3044 is a free end. The power supplycircuit 304 includes the rectifying diode 3041, an electric double layercapacitor 3042, and a voltage converting circuit 3043. One terminal ofthe electric double layer capacitor 3042 is connected to the cathode ofthe diode 3041. Another terminal of the electric double layer capacitor3042 is grounded. Incidentally, the power supply circuit 304 may be of acircuit configuration including a rechargeable storage battery. Thecontroller 301A makes the coil 75 function as an induction coil(wireless power feeding coil) or as an electrostatic shielding member bycontrolling the switch circuit 303A and the switch circuit 3044 by theswitching control signals SWA and SWB. Specifically, when the coil 75 ismade to function as a wireless power feeding coil based on anelectromagnetic induction system, the controller 301 connects themovable terminal a and the fixed terminal b of the switch circuit 3044to each other by controlling the switch circuit 3044 by the switchingsignal SWB, and connects the movable terminal a and the fixed terminal cof the switch circuit 303A to each other by controlling the switchcircuit 303A by the switching signal SWA. When the coil 75 is made tofunction as an electrostatic shielding member, the controller 301connects the movable terminal a and the fixed terminal c as a free endof the switch circuit 3044 to each other by controlling the switchcircuit 3044 by the switching signal SWB. The coil 75 can be made tofunction as an electrostatic shielding member when the movable terminala and the fixed terminal c of the switch circuit 303A are connected toeach other by the switching signal SWA, in the state in which themovable terminal a and the fixed terminal c as a free end of the switchcircuit 3044 are connected to each other. In addition, the function ofthe coil 75 as an electrostatic shielding member can be cleared when themovable terminal a and the fixed terminal b as a free end of the switchcircuit 303A are connected to each other by the switching signal SWA.

The controller 301A monitors output from the received signal detectingcircuit 305, and determines whether a coupled state enablingelectrostatic interaction is set between the position indicator 1A andthe sensor on the basis of whether the signal level of a received signalfrom the sensor has become equal to or higher than a predeterminedthreshold value level. Then, according to a result of the determination,an enable signal CTA that controls the oscillating circuit 302A iscontrolled, the movable terminal a and the fixed terminal c of theswitch circuit 3044 are connected to each other by the switching controlsignal SWB, and the switch circuit 303A is controlled by the switchingcontrol signal SWA. The predetermined threshold value at this time isdetermined in advance on the basis of a received signal level when thecoupled state enabling electrostatic interaction is set between theposition indicator 1A and the sensor. Incidentally, the coupled stateenabling electrostatic interaction between the position indicator 1A andthe sensor includes a state in which the tip portion 6Aa of the corebody 6A of the position indicator 1A is in proximity to the sensorsurface of the sensor without being in contact with the sensor surfaceof the sensor.

Then, when the coupled state enabling electrostatic interaction is setbetween the position indicator 1A and the sensor, the controller 301Amonitors for reception of a request signal from the position detectingdevice. The request signal from the position detecting device isreceived by the conductor sleeve 23 through electrostatic coupling tothe sensor, as described above. The request signal from the positiondetecting device, which request signal is received by the conductorsleeve 23, is supplied to the controller 301A through the receivedsignal detecting circuit 305. The received signal detecting circuit 305is also supplied with the voltage from the voltage converting circuit304 as power.

According to whether the request signal from the external device is notreceived or whether the request signal is received, the controller 301Acontrols the enable signal CTA that controls the oscillating circuit302A, and controls the switching control signal SWA for the switchcircuit 303A, as will be described later.

In this case, when the controller 301A determines that the requestsignal from the position detecting device is received, the controller301A controls the oscillating circuit 302A so as to send out a signalfrom the core body 6A, and controls the switch circuit 303A so as toswitch between two states, that is, a state in which the core body 6A iselectrostatically shielded by the shielding member 7A and a state inwhich the electrostatic shielding of the core body 6A by the shieldingmember 7A is cleared, as in the position indicator 1 according to theforegoing first embodiment.

The mode of the signal sent out from the core body 6A at this time maybe the mode of signal transmission control in the first example of theforegoing first embodiment, or may be the mode of signal transmissioncontrol in the second example. In the case where the first example isused, the signal in the above-described mode can be sent out from theposition indicator 1A to the sensor of the position detecting device intiming determined on the basis of the request signal. Thus, the shieldstate information SH does not need to be included in the signal sent outfrom the core body 6A.

In addition, the signal in the two states may not necessarily use themodes of signal transmission control in the first example and the secondexample described above. For example, only a signal for positiondetection, which signal does not include additional information such aspen pressure information or the like, may be transmitted in the twostates.

As will be described later, when the coupled state enablingelectrostatic interaction is not set between the position indicator 1Aand the sensor, the controller 301A connects the movable terminal a ofthe switch circuit 3044 to the fixed terminal b by the switching controlsignal SWB, and grounds the coil 75 through the switch circuit 303A byconnecting the movable terminal a of the switch circuit 303A to thefixed terminal c by the switching control signal SWA.

When the position indicator 1A is mounted on a charger not illustratedin the figure, which charger performs charging by an electromagneticinduction system in this state, an induced electromotive force isgenerated in the coil 75 by an alternating magnetic field produced bythe charger, and charges the electric double layer capacitor 3042 as acharger via the diode 3041.

The voltage converting circuit 3043 converts a voltage stored in theelectric double layer capacitor 3042 into a certain voltage, andsupplies the voltage as power to the controller 301A, the oscillatingcircuit 302A, and the received signal detecting circuit 305. The voltageconverting circuit 3043 may be a step-down type such as makes thevoltage lower than the voltage across the electric double layercapacitor 3042, or may be a step-up type such as makes the voltagehigher than the voltage across the electric double layer capacitor 3042.In addition, the voltage converting circuit 3043 may be astep-up/step-down type that operates as a step-down circuit when thevoltage across the electric double layer capacitor 3042 is higher than acertain voltage, and operates as a step-up circuit when the voltageacross the electric double layer capacitor 3042 is lower than thecertain voltage.

Next, referring to a flowchart of FIG. 10, description will be made of aflow of control processing of the controller 301A of the signaltransmission control circuit 30A of the position indicator 1A accordingto the second embodiment.

The controller 301A detects the signal level of a received signal fromthe sensor, which received signal is detected by the received signaldetecting circuit 305 (S101), and determines whether or not the detectedsignal level of the received signal is equal to or higher than apredetermined threshold value (S102).

When the controller 301A determines at S102 that the detected signallevel of the received signal is not equal to or higher than thepredetermined threshold value, the controller 301A determines that thecoupled state enabling electrostatic interaction is not set between theposition indicator 1A and the sensor, and performs control so as to stopsending out a signal from the oscillating circuit 302A by the enablesignal CTA, and connects the switch circuit 3044 to the fixed terminal bby the switching control signal SWB, and controls the switch circuit303A so as to connect the movable terminal a to the fixed terminal c bythe switching control signal SWA (S103). In this state, the coil 75 isgrounded through the switch circuit 303A. Thus, the electric doublelayer capacitor 3042 can be charged and made to store electricity bymounting the position indicator 1A on the charging device.

When the controller 301A determines at S102 that the detected signallevel of the received signal is equal to or higher than thepredetermined threshold value, the controller 301A determines that thecoupled state enabling electrostatic interaction is set between theposition indicator 1A and the sensor, connects the movable terminal a ofthe switch circuit 3044 to the fixed terminal c by the switching controlsignal SWB, and performs control so as to send out a signal from theoscillating circuit 302A as described above by the enable signal CTA.The state in which the movable terminal a of the switch circuit 303A isconnected to the fixed terminal c is maintained by the switching controlsignal SWA (S104).

Next, the controller 301A determines whether or not a request signal isreceived by monitoring the received signal from the sensor, whichreceived signal is detected by the received signal detecting circuit 305(S105). When the controller 301A determines at S105 that the requestsignal is not received, the controller 301A returns the processing toS101, and repeats the processing from S101 on down.

When the controller 301A determines at S105 that the request signal isreceived, the controller 301A supplies the above-described signal to thesensor of the position detecting device through the core body 6A in twostates, that is, the state in which the core body 6A iselectrostatically shielded by the shielding member 7A and the state inwhich the electrostatic shielding of the core body 6A by the shieldingmember 7A is cleared, as in the position indicator 1 according to theforegoing first embodiment (S106).

Next, the controller 301A determines whether or not a request endingsignal is received from the position detecting device (S107). When thecontroller 301A determines at S107 that the request ending signal is notreceived from the position detecting device, the controller 301A returnsthe processing to S105, and repeats the processing from S105 on down. Inaddition, when the controller 301A determines at S107 that the requestending signal is received from the position detecting device, thecontroller 301A returns the processing to S101, and repeats theprocessing from S101 on down.

According to the position indicator 1A in accordance with the foregoingsecond embodiment, when an inclination angle detection request signal isreceived from the position detecting device, it suffices to perform asignal sequence so as to produce two states, that is, the state in whichthe core body 6A is electrostatically shielded by the shielding member7A and the state in which the electrostatic shielding of the core body6A by the shielding member 7A is cleared, in response to the receivedinclination angle detection request signal.

In addition, according to the position indicator 1A in accordance withthe foregoing second embodiment, the coil 75 is used as the shieldingmember 7A for electrostatically shielding the core body 6A, and the coil75 is used as a coil for noncontact charging. Thus, in addition to theeffect of electrostatically shielding the core body 6A, it is possibleto realize a position indicator with good operability, which positionindicator is capable of noncontact charging by, for example, a chargerof a pen stand shape or the like.

Modifications of Second Embodiment

In the foregoing second embodiment, the coupled state enablingelectrostatic interaction between the position indicator 1A and thesensor is detected on the basis of the signal level of a signal receivedfrom the sensor through the conductor sleeve. However, the coupled statemay be detected by detecting a state of touching the sensor on the basisof pen pressure detection by the pen pressure detector 5A, as in thefirst embodiment.

Incidentally, while the conductor sleeve 23 is dedicated to reception,the conductor sleeve 23 can also be used for transmission of the signalfrom the oscillating circuit 302A. Specifically, in that case, thecircuit is configured such that the conductor sleeve 23 can be timedivision controlled in a transmission time interval for performingsignal transmission and a reception time interval for receiving a signalfrom the sensor. Then, a signal is transmitted in the transmission timeinterval before the coupled state as a state enabling electrostaticinteraction between the position indicator and the sensor is detectedfrom the received signal in the reception time interval. A signal fromthe position indicator can thereby be sent out from the core body andthe conductor sleeve. Thus, signal sending-out energy in a so-calledhovering state before the position indicator is coupled to the sensorcan be increased, and detection of the position of the positionindicator in the hovering state becomes relatively easy. Then, after theposition indicator and the sensor are set in the coupled state, only thereception time interval is set to monitor the signal from the sensor ofthe position detecting device at all times, and request signaldetermination is made.

In addition, in the foregoing second embodiment, description has beenmade of control performed in response to a request signal from theposition detecting device side so as to produce two states as one pair(one set), the two states being a state in which the core body iselectrostatically shielded and a state in which the electrostaticshielding is cleared, while a signal is sent out from the core body.However, control may be performed so as to normally send out a signalfrom the core body in the electrostatically shielded state, and clearthe electrostatic shielding when there is a request signal from theposition detecting device side. In addition, conversely, control may beperformed so as to normally send out a signal from the core body in thestate in which the electrostatic shielding is cleared, and perform theelectrostatic shielding when there is a request signal from the positiondetecting device side.

In that case, it suffices for the position detecting device to retain,in advance, the peak value of the received signal from the positionindicator, which signal is detected during the normal time, and detectthe inclination angle of the axial direction of the core body of theposition indicator from a difference between the retained peak value andthe peak value of the received signal received after the request signalis sent out.

Incidentally, one terminal 75 a of the coil 75 at a time of theelectrostatic shielding of the core body 6A of the position indicator 1Aby the coil 75 is not limited to a ground potential, but may be apositive side potential of the power supply, or may be a potentialintermediate between the positive side potential of the power supply andthe ground potential. In short, it suffices to ground one terminal 75 aof the coil 75 in terms of alternating current.

In addition, in the foregoing second embodiment, the conductor sleeve 23formed of a conductor is provided on the pen tip side of the positionindicator 1A, and the request signal for detection of the inclinationangle of the position indicator 1A (core body 6A) from the positiondetecting device is received by the conductor sleeve 23 by electrostaticcoupling to the sensor. However, the reception of the request signalfrom the position detecting device in the position indicator 1A is notlimited to the present example.

For example, as illustrated in FIG. 11 in which the same parts as in theposition detecting device 201 described with reference to FIG. 5 areidentified by the same reference numerals, and description thereof willbe omitted, the position indicator 1A is provided with wirelesscommunication means capable of two-way communication, for example, awireless communication device 9 that communicates according to aBluetooth (registered trademark) standard, and the position detectingdevice is also provided with wireless communication means, for example,a wireless communication device 227 that communicates according to theBluetooth (registered trademark) standard. Then, the control circuit 220of the position detecting device 201 supplies a request signal to theposition indicator 1A through the wireless communicating unit 227, intiming of detecting the inclination angle of the axial direction of thecore body 6A of the position indicator 1A.

Then, the position indicator 1A receives the request signal from theposition detecting device by the wireless communicating unit 9, and thecontroller 301A not illustrated in FIG. 11 controls the oscillatingcircuit 302A as described above.

Incidentally, the wireless communication devices are not limited towireless communication devices using radio waves as in the example ofFIG. 11, but may, for example, be wireless communication units usingoptical communication by infrared rays or the like, ultrasonic waves, orthe like.

Incidentally, when signals for detecting the inclination angle of thecore body are sent out from the position indicator side in response tothe request signal from the position detecting device, the positionindicator in the foregoing second embodiment executes two states, thatis, a state in which a signal is sent out in the state in which the corebody is electrostatically shielded, and a state in which a signal issent out in the state in which the electrostatic shielding of the corebody is cleared. However, the position indicator may always send out asignal in one of the state in which the core body is electrostaticallyshielded or the state in which the electrostatic shielding of the corebody is cleared while the request signal is not received, and send out asignal in the other of the state in which the core body iselectrostatically shielded or the state in which the electrostaticshielding of the core body is cleared when the request signal isreceived. In this case, the position detecting device can detect theinclination angle of the core body of the position indicator from thereceived signal before the request signal is sent out, and from thereceived signal after the request signal is sent out.

THIRD EMBODIMENT

A third embodiment to be described in the following is an example of aconfiguration enabling detection of not only the inclination angle ofthe axial direction of the core body of the position indicator but alsorotation of the position indicator.

FIG. 12A is an enlarged sectional view of the pen tip side of a positionindicator 1B according to the third embodiment. In addition, FIGS. 12Band 12C are diagrams illustrating an example of constitution of parts ofthe position indicator 1B according to the third embodiment.

As with the core body 6A of the position indicator 1A according to thesecond embodiment, a core body 6B of the position indicator 1B accordingto the present third embodiment is formed by a rod-shaped body of aconductor formed of a conductive metal or a conductive resin. Asillustrated in FIG. 12A, the position indicator 1B according to thepresent third embodiment uses a pen pressure detector 5B to detect a penpressure applied to the core body 6B. As in the first embodiment, thecore body 6B is covered by a tubular shielding member 7B except for thepen tip side and the fitting side of the core body 6B, the fitting sidebeing fitted to the pen pressure detector 5B.

The pen pressure detector 5B includes an outside holder 57 and an insideholder 58 formed of a resin, for example, and a pressure sensing device59.

The outside holder 57 has a through hole 572 through which the core body6B is inserted and a housing space 573 formed by a hollow portioncommunicating with the through hole 572. The inside holder 58 and thepressure sensing device 59 disposed in the inside holder 58 are housedwithin the housing space 573. In addition, a recessed portion 571 havinga shape corresponding to the shielding member 7B is provided in an endsurface on the pen tip side of the outside holder 57. An end portion ofthe shielding member 7B, which end portion is on an opposite side fromthe pen tip side of the shielding member 7B, is fitted and coupled tothe inside of the recessed portion 571.

In the position indicator 1B according to the present third embodiment,as illustrated in FIG. 12B, the shielding member 7B is provided withthree electrodes 71Ba, 71Bb, and 71Bc in the outer circumferentialsurface of a tubular body 72B formed of an insulating material, forexample, a resin. As illustrated in FIG. 12A, the shielding member 7B isdisposed within a casing 2B in a state in which the axial direction ofthe shielding member 7B and the axial direction of the casing 2Bcoincide with each other. The shielding member 7B has a through hole 7Bahaving a diameter for inserting the core body 6B.

As illustrated in FIG. 12B, the electrodes 71Ba, 71Bb, and 71Bc areconstituted by conductive metallic conductors formed so as to beelectrically separated from each other in the outer circumferentialsurface of the tubular body 72B, with each of the metallic conductors inan angle range slightly narrower than an angle range of 120 degrees.That is, the electrodes 71Ba, 71Bb, and 71Bc are equivalent toelectrodes obtained by dividing the tubular conductor 71 of theshielding member 7 in the first embodiment into three parts in acircumferential direction. Incidentally, the tubular body 72B formed ofa resin as an insulating material corresponds to the insulating layer 72of the shielding member 7 in the first embodiment.

As illustrated in FIG. 12C, conductor pieces 5711, 5712, and 5713corresponding to the three electrodes 71Ba, 71Bb, and 71Bc formed in theouter circumferential surface of the tubular body 72B of the shieldingmember 7B are formed on an inner circumferential surface on the bottomsurface side of the recessed portion 571 of the outside holder 57 of thepen pressure detector 5B. In addition, a protrusion 7Bb for alignment isformed on the tubular body 72B of the shielding member 7B, and arecessed hole 571 d corresponding to the protrusion 7Bb is formed in thebottom surface of the recessed portion 571, as illustrated in FIG. 12C.When the protrusion 7Bb is fitted into the recessed hole 571 d,alignment in the circumferential direction is performed, and the tubularbody 72B of the shielding member 7B is housed within the recessedportion 571. Then, the three electrodes 71Ba, 71Bb, and 71Bc formed inthe outer circumferential surface of the tubular body 72B of theshielding member 7B and the corresponding conductor pieces 5711, 5712,and 5713 of the recessed portion 571 respectively come into contact witheach other, and are thus electrically connected to each other.

As illustrated in FIG. 12A, connecting lines (see dotted lines in FIG.12A) 5711 a, 5712 a, and 5713 a having one ends connected to therespective conductor pieces 5711, 5712, and 5713 are provided by insertmolding within the outside holder 57 formed of a resin. Other ends ofthe connecting lines 5711 a, 5712 a, and 5713 a are connected to asignal transmission control circuit 30B (see FIG. 13) disposed on aprinted circuit board 3B. Thus, when the shielding member 7B is fittedand housed within the recessed portion 571, the three electrodes 71Ba,71Bb, and 71Bc formed in the outer circumferential surface of theshielding member 7B are connected to the signal transmission controlcircuit 30B disposed on the printed circuit board 3B through theconductor pieces 5711, 5712, and 5713 and the connecting lines 5711 a,5712 a, and 5713 a.

As illustrated in FIG. 12A, the outside holder 57 on the side of thecore body 6B in the axial direction abuts against a stepped portion 2Bcof the casing 2B, and the outside holder 57 on an opposite side from thecore body 6B also abuts against axial direction position regulatingmeans, so that the outside holder 57 is fixed so as not to move in theaxial direction within the casing 2B. An end portion on the pen tip sideof the shielding member 7B abuts against a stepped portion 2Bb providedin the vicinity of an opening portion 2Ba on the pen tip side of thecasing 2B. Thus, the shielding member 7B fitted to the outside holder 57is also fixed so as not to move in the axial direction within the casing2B.

The housing space 573 of the outside holder 57 on the side where thecore body 6B is inserted has a smaller diameter than the diameter of theinside holder 58, and the through hole 572 has a larger diameter thanthe diameter of the core body 6B. Hence, a stepped portion 574 is formedin the housing space 573 of the outside holder 57. The stepped portion574 prevents the inside holder 58 housed within the housing space 573from falling off from the outside holder 57 to the core body 6B side.

As illustrated in FIG. 12A, the inside holder 58 holds the pressuresensing device 59 constituting a pen pressure detecting element. Thepressure sensing device 59 is formed by a semiconductor chipconstituting a capacitance type pressure sensing unit. The pressuresensing device 59 is configured as a variable capacitance capacitorconstituted of a MEMS (Mico Electro Mechanical Systems) element, thevariable capacitance capacitor having a capacitance variable accordingto a pen pressure as disclosed in Japanese Patent Laid-Open No.2013-161307, for example. The pressure sensing device 59 can be formedby using a semiconductor element. The configuration of the pressuresensing device 59 is described in the above-described publication, andtherefore description thereof will be omitted here. Though notillustrated, two electrodes of the variable capacitance capacitor formedby the pressure sensing device 59 are connected to the signaltransmission control circuit 30B formed on the printed circuit board 3B.

A pressure transmitting member 8B for transmitting a pressure applied tothe core body 6B to the pressure sensing device 59 held by the insideholder 58 is also provided in the housing space 573 of the outsideholder 57.

The pressure transmitting member 8B is constituted of a core bodyfitting portion 81B into which the core body 6B is fitted and a pressingportion 82B that presses the pressure sensing device 59. The pressingportion 82B has a projecting portion 82Ba that presses the pressuresensing device 59. The core body fitting portion 81B has a recessed hole81Ba into which the core body 6B is inserted and fitted. An end portion6Ba of the core body 6B, which end portion is on an opposite side fromthe pen tip side of the core body 6B, is inserted and detachably fittedinto the recessed hole 81Ba.

In the present embodiment, a conductor layer 53Ba is deposited andformed on the wall surface of the through hole 572 of the outside holder57 by printing, deposition, or the like, and a conductor brush 53Bb isformed from the conductor layer 53Ba. Within the outside holder 57, asillustrated in FIG. 12A, a connecting line 53Bc for connecting theconductor layer 53Ba and the signal transmission control circuit 30B onthe printed circuit board 3 is provided by insert molding, for example.

Hence, when the core body 6B as a conductor is inserted through thethrough hole 572 of the outside holder 57, and fitted into the core bodyfitting portion 81B of the pressure transmitting member 8B, the corebody 6B is electrically connected to the conductor layer 53Ba via theconductor brush 53Bb of the through hole 572, as illustrated in FIG.12A. Consequently, the core body 6B as a conductor is connected to anoutput terminal of an oscillating circuit in the signal transmissioncontrol circuit 30B on the printed circuit board 3B, and the core body6B operates as a signal electrode.

In the position indicator 1B according to the third embodiment having aconfiguration as described above, when a pen pressure is applied to thecore body 6B, the pressure transmitting member 8B engaged with the corebody 6B in the pen pressure detector 5B is displaced within the outsideholder 57 so as to press the pressure sensing device 59 in the axialdirection according to the applied pen pressure. The capacitance of thevariable capacitance capacitor formed between the two electrodes of thepressure sensing device 59 therefore changes according to the penpressure. The position indicator 1B detects the pen pressure applied tothe core body 6B on the basis of the change in the capacitance as in theforegoing, disposes the detected pen pressure data as an ASK modulatedsignal in the transmission period of additional information, and sendsout the ASK modulated signal to the position detecting device.

The signal transmission control circuit 30B of the position indicator 1Baccording to the present third embodiment performs switching control ofthe three electrodes 71Ba, 71Bb, and 71Bc of the shielding member 7B ina state of sending out a signal to the sensor of the position detectingdevice through the core body 6B. Thus, from the signal received from theposition indicator 1B, the position detecting device 201 detects aposition indicated by the position indicator 1B, and detects theinclination angle and rotation angle of the position indicator 1B. Inthe following, description will be made of an example of constitutionand operation of the signal transmission control circuit 30B of theposition indicator 1B according to the present third embodiment.

[Example of Constitution and Example of Operation of Signal TransmissionControl Circuit 30B of Position Indicator 1B According to ThirdEmbodiment]

FIG. 13 illustrates an example of constitution of the signaltransmission control circuit 30B of the position indicator 1B accordingto the third embodiment. In FIG. 13, the same parts as in the signaltransmission control circuit 30 of the position indicator 1 according tothe first embodiment described with reference to FIG. 3 are identifiedby the same reference numerals, and description thereof will be omitted.

A controller 301B is formed by a microprocessor as with the controller301 in the first embodiment. The controller 301B is different from thecontroller 301 in the first embodiment only in terms of a manner ofcontrol of electronic parts connected to the controller 301B.

The controller 301B is supplied with a power supply voltage VDD from abattery 4 as a power supply circuit, and is connected with anoscillating circuit 302. The controller 301B supplies an enable signalCTB as a control signal to the oscillating circuit 302. In addition, thecontroller 301B is connected with a variable capacitance capacitor 59Cformed by the pressure sensing device 59 of the pen pressure detector5B, and a discharging resistor Rd is connected in parallel with thevariable capacitance capacitor 59C.

In the third embodiment, the signal transmission control circuit 30B isprovided with three switch circuits 303Ba, 303Bb, and 303Bc forswitching respective electric states of the three electrodes 71Ba, 71Bb,and 71Bc of the shielding member 7B. The three electrodes 71Ba, 71Bb,and 71Bc are respectively connected to the respective movable terminalsa of the three switch circuits 303Ba, 303Bb, and 303Bc.

The switch circuits 303Ba, 303Bb, and 303Bc each have a fixed terminal bsupplied with a signal from the oscillating circuit 302, have a fixedterminal c grounded, and have a fixed terminal d as a free end. Theswitch circuit 303Ba is supplied with a switching control signal SWafrom the controller 301B, the switch circuit 303Bb is supplied with aswitching control signal SWb from the controller 301B, and the switchcircuit 303Bc is supplied with a switching control signal SWc from thecontroller 301B. The switch circuits 303Ba, 303Bb, and 303Bc are therebyswitching-controlled.

In the present third embodiment, the position indicator 1B notifies astate of shielding of the core body 6B by the shielding member 7B to thesensor of the position detecting device 201 by using the second exampleof the signal transmission control method in the first embodiment.

In addition, in the present third embodiment, the signal from theoscillating circuit 302 is sent out not only from the core body 6B butalso from the three electrodes 71Ba, 71Bb, and 71Bc of the shieldingmember 7B in a so-called hovering state, in which the tip portion of thecore body 6B of the position indicator 1B is not in contact with thesensor of the position detecting device 201. The position detectingdevice 201 can thereby detect the position of the position indicator 1Beven when the position indicator 1B is in the hovering state.

Incidentally, in the present example, the controller 301B determineswhether or not the position indicator 1B is in the hovering state on thebasis of a pen pressure detected on the basis of the capacitance of thepressure sensing device 59 of the pen pressure detector 5B.

FIG. 14 is a flowchart of assistance in explaining an example ofprocessing operation of the controller 301B of the signal transmissioncontrol circuit 30B of the position indicator 1B according to thepresent third embodiment. In addition, FIG. 15 is a timing diagram ofassistance in explaining a signal transmission control method in thesignal transmission control circuit 30B when the tip portion of the corebody 6B of the position indicator 1B is in contact with the sensor ofthe position detecting device 201. In the following, referring to FIG.14 and FIG. 15, description will be made of the transmission signalcontrol method in the signal transmission control circuit 30B of theposition indicator 1B according to the present third embodiment.

As illustrated in FIG. 14, the controller 301B determines whether or notpower supply is on, on the basis of whether the power switch Psw is on(S201). When the controller 301B determines at S201 that the power ison, the controller 301B sends out a signal from the core body 6B byperforming control so as to send out the signal in the hovering state bythe enable signal CTB supplied to the oscillating circuit 302, andperforms control so as to send out the signal in the hovering state fromall of the three electrodes 71Ba, 71Bb, and 71Bc byswitching-controlling the movable terminals a of the switch circuits303Ba, 303Bb, and 303Bc to a state of being connected to the fixedterminals b by the switching control signals SWa, SWb, and SWc (S202).Here, the signal in the hovering state is, for example, a signal such asrepeats a burst signal not including additional information such as penpressure information or the like in predetermined cycles.

Then, the controller 301B determines whether or not a pen pressure isdetected, by detecting the capacitance of the variable capacitancecapacitor 59C formed by the pressure sensing device 59 of the penpressure detector 5 as described above (S203). When the controller 301Bdetermines at S203 that no pen pressure is detected, the controller 301Breturns the processing to S202, and repeats the processing from S202 ondown.

When the controller 301B determines at S203 that a pen pressure isdetected and that the pen tip of the core body 6B of the positionindicator 1B is therefore in contact with the sensor surface of thesensor of the position detecting device 201, the controller 301Bsequentially performs S204 to S207, and thereby performs signaltransmission control to make the position detecting device 201 detect aposition indicated by the position indicator 1B, and make the positiondetecting device 201 detect the inclination angle of the axial directionof the core body 6B of the position indicator 1B with respect to thesensor surface and the rotation of the position indicator 1B, as will bedescribed in the following.

This signal transmission control is performed by repeating, as one cycleTc, a period constituted of a transmission period PBs of a signal forposition detection and a transmission period PBad of additionalinformation as illustrated in portion (A) of FIG. 15. In this case, thetransmission period PBs of the signal for position detection is a periodhaving a length five times that of the sending-out period of the signalfor position detection in which period a position indicated by theposition indicator 1B can be detected on the position detecting deviceside, as described with reference to portions (A) and (C) of FIG. 6. Thetransmission period PBad of the additional information may be similar tothe transmission period of the additional information as described withreference to portions (A) and (C) of FIG. 6.

When the controller 301B determines at S203 that a pen pressure isdetected, as illustrated in FIG. 15, the controller 301B sends out asignal for position detection from the oscillating circuit 302, andgrounds all of the three electrodes 71Ba, 71Bb, and 71Bc byswitching-controlling the movable terminals a of the switch circuits303Ba, 303Bb, and 303Bc to a state of being connected to the fixedterminals c by the switching control signal SWa (see portion (B) of FIG.15), the switching control signal SWb (see portion of (C) of FIG. 15),and the switching control signal SWc (see portion (D) of FIG. 15) in afirst sending-out period P1 having ⅕ of the length of the transmissionperiod PBs (S204). The core body 6B thereby sends out the signal forposition detection to the sensor through the core body 6B in a state inwhich electrostatic shielding is performed by the three electrodes 71Ba,71Bb, and 71Bc (shield on).

Next, when the first sending-out period P1 is ended, and a secondtransmission period P2 having ⅕ of the length of the transmission periodPBs arrives, the controller 301B sets all of the three electrodes 71Ba,71Bb, and 71Bc in a state of floating in terms of potential byswitching-controlling the movable terminals a of the switch circuits303Ba, 303Bb, and 303Bc to a state of being connected to the fixedterminals d by the switching control signal SWa (see portion (B) of FIG.15), the switching control signal SWb (see portion (C) of FIG. 15), andthe switching control signal SWc (see portion of (D) FIG. 15) (S205).The core body 6B thereby sends out the signal for position detection tothe sensor through the core body 6B in a state in which theelectrostatic shielding by the three electrodes 71Ba, 71Bb, and 71Bc iscleared.

As described above, the position detecting device detects a receivedsignal as the signal from the position indicator 1B in the transmissionperiod P1, and can detect a position indicated by the position indicator1B from the level of the received signal. In addition, the positiondetecting device detects received signals as the signals from theposition indicator 1B in the two transmission periods, that is, thetransmission period P1 and the transmission period P2, and can detectthe inclination angle of the axial direction of the core body 6B of theposition indicator 1B with respect to the sensor surface from adifference between positions on the sensor, at which positions thelevels of the received signals exhibit peak values.

Next, after the second sending-out period P2 is ended, the controller301B controls one of the three electrodes 71Ba, 71Bb, and 71Bc to agrounded state in each of a third transmission period P3, a fourthtransmission period P4, and a fifth transmission period P5 each having ⅕of the length of the transmission period PBs (S206). Specifically, inthe example of FIG. 15, in the third transmission period P3, control isperformed so as to connect the movable terminal a of the switch circuit303Ba to the fixed terminal c by the switching control signal SWa (seeportion (B) of FIG. 15), and connect the movable terminals a of theswitch circuit 303Bb and the switch circuit 303Bc to the fixed terminalsd by the switching control signal SWb (see portion (C) of FIG. 15) andthe switching control signal SWc (see portion (D) of FIG. 15).

Thus, the core body 6B is electrostatically shielded by only one of thethree electrodes 71Ba, 71Bb, and 71Bc in each of the third transmissionperiod P3, the fourth transmission period P4, and the fifth transmissionperiod P5. Hence, the position detecting device receives a receivedsignal differing according to the electrode acting as an electrostaticshield and the electrodes in which electrostatic shielding is cleared ineach of the third transmission period P3, the fourth transmission periodP4, and the fifth transmission period P5. Hence, the position detectingdevice can detect in which direction and to which degree the positionindicator 1B is rotated according to a change in the received signal.

Next, when the fifth sending-out period P5 is ended and the transmissionperiod PBad of additional information arrives, the controller 301Bcontrols the oscillating circuit 302 so as to send out the additionalinformation constituted of pen pressure data or the like, and groundsall of the three electrodes 71Ba, 71Bb, and 71Bc byswitching-controlling the movable terminals a of the switch circuits303Ba, 303Bb, and 303Bc to a state of being connected to the fixedterminals c by the switching control signal SWa (see portion (B) FIG.15), the switching control signal SWb (see portion (C) of FIG. 15), andthe switching control signal SWc (see portion (D) of FIG. 15) (S204).The core body 6B thereby sends out the additional information to thesensor through the core body 6B in a state in which electrostaticshielding is cleared by the three electrodes 71Ba, 71Bb, and 71Bc(shield off).

Hence, the position detecting device can detect the additionalinformation from the position indicator 1B.

Next, the controller 301B determines whether or not disappearance of thepen pressure applied to the core body 6B has continued for apredetermined time or more (S208). When the disappearance of the penpressure has not continued for the predetermined time or more, thecontroller 301B returns the processing to S204, and repeats thetransmission control processing operation in the above-described cycleTc from S204 on down. In addition, when the controller 301B determinesthat the disappearance of the pen pressure has continued for thepredetermined time or more, the controller 301B returns the processingto S202, and repeats the processing from S202 on down.

Here, the predetermined time for which the disappearance of the penpressure is determined to have continued at S208 is a time such that theuser temporarily stops indication input on the sensor surface by theposition indicator 1B. Therefore, when the user temporarily separatesthe position indicator 1B from the sensor surface and immediatelyperforms indication input by bringing the position indicator 1B intocontact with the sensor surface again, the operation of repeating theabove-described cycle Tc can be continued assuming the state in whichthe pen pressure is detected. This is thus convenient.

According to the position indicator 1B in accordance with the foregoingthird embodiment, the position detecting device can detect not only theinclination angle of the core body 6B of the position indicator 1B withrespect to the sensor surface but also the rotation of the positionindicator 1B. Though inclination detection accuracy is decreased, it isalso possible to omit the shield-off period in the interval forinclination angle detection, and calculate the inclination angle fromthe signals detected during the interval for rotation detection.

Modifications of Third Embodiment

The foregoing third embodiment notifies the state of shielding of thecore body 6B by the shielding member 7B, by using the second example ofthe signal transmission control method in the first embodiment. However,it is also possible to apply the first example of the signaltransmission control method in the first embodiment. In that case, itsuffices to include, in the signal sent out from the position indicator1B, information notifying the position detecting device of the state ofelectrostatic shielding by all of the three electrodes 71Ba, 71Bb, and71Bc and the state of electrostatic shielding by each electrode.

In addition, also in the third embodiment, as in the second embodiment,signal sending-out control for detecting the inclination angle and therotation may be performed in response to a request signal from theposition detecting device side. In that case, as in the secondembodiment, a method may be adopted in which a conductor such as aconductor sleeve or the like is provided to the pen tip side of thecasing of the position indicator as in the second embodiment, and therequest signal from the position detecting device is received byelectrostatic coupling between the conductor sleeve and the sensor ofthe position detecting device, or as illustrated in FIG. 11, the requestsignal may be sent and received by communication between the positionindicator and the position detecting device using wireless communicationmeans using radio waves or the like.

In addition, without the conductor sleeve being provided, the core bodymay be controlled on a time-division basis for signal transmission andfor receiving the request signal from the position detecting device.This can be applied also to the case of the foregoing second embodiment.

Incidentally, in the foregoing third embodiment, three electrodes areprovided by dividing the conductor of the shielding member into threeparts in the circumferential direction in order to make the positiondetecting device detect rotation of the position indicator. However, thenumber of divisions of the conductor may be any number as long as thenumber is two or more.

Other Embodiments or Modifications

Incidentally, the coupled state enabling electrostatic interactionbetween the position indicator and the sensor of the position detectingdevice may be detected as a state of touching the sensor on the basis ofpen pressure detection by the pen pressure detector 5, or may bedetected on the basis of the level of a signal received from the sensorthrough the conductor sleeve or the core body.

In the case where the position indicator and the position detectingdevice are connected to each other by wireless communication means usingradio waves, whether the coupled state enabling electrostaticinteraction between the position indicator and the sensor of theposition detecting device is set may be determined on the positiondetecting device side, and when the coupled state is determined, thecoupled state may be notified to the position indicator by wirelesscommunication.

In the foregoing embodiments, the pen pressure detector uses a member oran element constituting a variable capacitance capacitor in order todetect a pen pressure applied to the core body. However, withoutlimitation to this, a structure or an element having an inductance valueor a resistance value variable according to a pen pressure may be used.

DESCRIPTION OF REFERENCE SYMBOLS

1, 1A, 1B . . . Position indicator, 2 . . . Casing, 3 . . . Printedcircuit board, 5, 5A, 5B . . . Pen pressure detector, 6, 6A, 6B . . .Core body, 7, 7A, 7B . . . Shielding member, 8 . . . Pressuretransmitting member, 9 . . . Wireless communicating unit, 30, 30A, 30B .. . Signal transmission control circuit, 301, 301A, 301B . . .Controller, 302, 302A . . . Oscillating circuit, 304 . . . Power supplycircuit, 305 . . . Received signal detecting circuit, 303, 303A, 303Ba,303Bb, 303Bc . . . Switch circuit

The invention claimed is:
 1. A position indicator that electrostaticallyinteracts with a position detecting device including a sensor, theposition indicator comprising: a casing having a pen shape; a conductivecore body including a pen tip that protrudes from an opening on one endin an axial direction of the casing; a first conductor surrounding theconductive core body; a signal generating circuit which, in operation,generates a signal that is supplied to the conductive core body forelectrostatically interacting with the sensor of the position detectingdevice; a power supply circuit having a charging element that isselectively electrically coupled to the first conductor surrounding theconductive core body; and a control circuit which, in operation,electrically controls the conductive core body and the first conductorsurrounding the conductive core body, wherein the first conductorsurrounding the conductive core body has a coil shape and is used toelectromagnetically charge the charging element in the power supplycircuit, wherein the control circuit, in operation, electricallycontrols the first conductor having the coil shape and surrounding theconductive core body in response to receiving a request signaltransmitted from an external device, wherein the request signal requestsone or more of: charging of the charging element of the power supplycircuit, electrostatic transmission of the signal generated by thesignal generating circuit to the position detecting device, andelectrostatic shielding of the conductive core body, wherein, when therequest signal requests electromagnetic charging of the charging elementof the power supply circuit, the control circuit, in operation,electrically controls the first conductor having the coil shape andsurrounding the conductive core body, while the conductive core body isnot electrostatically shielded, and wherein the control circuit, inoperation, electrically controls the first conductor having the coilshape and surrounding the conductive core body such that electromagneticcharging of the charging element of the power supply circuit andelectrostatic shielding of the conductive core body are conducted in atime-divisional fashion.
 2. The position indicator according to claim 1,wherein the external device includes the position detecting device. 3.The position indicator according to claim 1, wherein the chargingelement is a rechargeable secondary battery or a capacitor.
 4. Theposition indicator according to claim 1, wherein, when the requestsignal requests electrostatic charging of the charging element of thepower supply circuit, the control circuit, in operation, electricallycontrols the first conductor having the coil shape and surrounding theconductive core body, while the signal generated by the signalgenerating circuit is not electrostatically transmitted to the positiondetecting device using the first conductor.
 5. The position indicatoraccording to claim 4, wherein the control circuit, in operation,electrically controls the first conductor having the coil shape andsurrounding the conductive core body such that electromagnetic chargingof the charging element of the power supply circuit and electrostatictransmission of the signal to the position detecting device areconducted in a time-divisional fashion.
 6. The position indicatoraccording to claim 1, wherein the request signal from the externaldevice is received electrostatically.
 7. The position indicatoraccording to claim 1, wherein the request signal from the externaldevice is received wirelessly via a radio signal receiving circuit. 8.The position indicator according to claim 7, wherein the radio signalreceiving circuit receives the request signal using a Bluetoothprotocol.
 9. A position indicator that electrostatically interacts witha position detecting device including a sensor, the position indicatorcomprising: a casing having a pen shape; a conductive core bodyincluding a pen tip that protrudes from an opening on one end in anaxial direction of the casing; a first conductor surrounding theconductive core body; a signal generating circuit which, in operation,generates a signal that is supplied to the conductive core body forelectrostatically interacting with the sensor of the position detectingdevice; a power supply circuit having a charging element that isselectively electrically coupled to the first conductor surrounding theconductive core body; and a control circuit which, in operation,electrically controls the conductive core body and the first conductorsurrounding the conductive core body, wherein the first conductorsurrounding the conductive core body has a coil shape and is used toelectromagnetically charge the charging element in the power supplycircuit, wherein the control circuit, in operation, electricallycontrols the first conductor having the coil shape and surrounding theconductive core body in response to receiving a request signaltransmitted from an external device, wherein the request signal requestsone or more of: charging of the charging element of the power supplycircuit, electrostatic transmission of the signal generated by thesignal generating circuit to the position detecting device, andelectrostatic shielding of the conductive core body, and wherein, whenthe request signal requests electrostatic shielding of the conductivecore body, the control circuit, in operation, electrically controls thefirst conductor having the coil shape and surrounding the conductivecore body, while the signal supplied to the conductive core body fromthe signal generating circuit is electrostatically transmitted to theposition detecting device from the conductive core body.
 10. A positionindicator that electrostatically interacts with a position detectingdevice including a sensor, the position indicator comprising: a casinghaving a pen shape; a conductive core body including a pen tip thatprotrudes from an opening on one end in an axial direction of thecasing; a first conductor surrounding the conductive core body; a signalgenerating circuit which, in operation, generates a signal that issupplied to the conductive core body for electrostatically interactingwith the sensor of the position detecting device; a power supply circuithaving a charging element that is selectively electrically coupled tothe first conductor surrounding the conductive core body; and a controlcircuit which, in operation, electrically controls the conductive corebody and the first conductor surrounding the conductive core body,wherein the first conductor surrounding the conductive core body has acoil shape and is used to electromagnetically charge the chargingelement in the power supply circuit, wherein the control circuit, inoperation, electrically controls the first conductor having the coilshape and surrounding the conductive core body in response to receivinga request signal transmitted from an external device, wherein therequest signal requests one or more of: charging of the charging elementof the power supply circuit, electrostatic transmission of the signalgenerated by the signal generating circuit to the position detectingdevice, and electrostatic shielding of the conductive core body, andwherein the control circuit, in operation, electrically controls theconductive core body and the first conductor having the coil shape andsurrounding the conductive core body such that the signal generated bythe signal generating circuit is transmitted from the conductive corebody in a time-divisional fashion to the position detecting device inresponse to receiving a request signal that requests tilt angleinformation indicating a tilt angle of the position indicator on theposition detecting device.
 11. A position indicator thatelectrostatically interacts with a position detecting device including asensor, the position indicator comprising: a casing having a pen shape;a conductive core body including a pen tip that protrudes from anopening on one end in an axial direction of the casing; a conductorsleeve surrounding the conductive core body; a first conductor having acoil shape installed in the casing of the position indicator; a signalgenerating circuit which, in operation, generates a signal that issupplied to the conductive core body for electrostatically interactingwith the sensor of the position detecting device; a power supply circuithaving a charging element that is electrically coupled to the firstconductor having the coil shape; and a control circuit which, inoperation, controls the conductive core body, the conductor sleeve, andthe first conductor having the coil shape in response to receiving arequest signal transmitted from an external device; wherein theconductive core body is controlled to electrostatically transmit thesignal supplied from the signal generating circuit to the positiondetecting device, wherein the conductor sleeve surrounding theconductive core body is controlled at least to receive the requestsignal transmitted from the external device, and wherein the firstconductor having the coil shape is controlled to conduct electromagneticcharging of the charging element of the power supply circuit for drivingthe position indicator.
 12. The position indicator according to claim11, wherein the external device includes the position detecting device.13. The position indicator according to claim 11, wherein the chargingelement is a rechargeable secondary battery or a capacitor.
 14. Theposition indicator according to claim 11, wherein the conductor sleevesurrounding the conductive core body is further controlled to transmitthe signal generated by the signal generating circuit forelectrostatically interacting with the sensor of the position detectingdevice.
 15. The position indicator according to claim 14, wherein signalreception and signal transmission through the conductor sleevesurrounding the conductive core body are controlled by the controlcircuit in response to receiving a request signal transmitted from theposition detecting device.
 16. The position indicator according to claim15, wherein signal reception and signal transmission through theconductor sleeve surrounding the conductive core body are controlled bythe control circuit in a time-divisional fashion.
 17. The positionindicator according to claim 11, wherein the request signal transmittedfrom the external device is received electrostatically.
 18. The positionindicator according to claim 11, wherein the request signal transmittedfrom the external device is received wirelessly via a radio signalreceiving circuit.
 19. The position indicator according to claim 18,wherein the radio signal receiving circuit receives the request signalusing a Bluetooth protocol.
 20. The position indicator according toclaim 11, wherein the control circuit, in operation, electricallycontrols the conductive core body and the first conductor having thecoil shape and surrounding the conductive core body to transmit thesignal supplied from the signal generating circuit to the positiondetecting device in a time-divisional fashion in response to receiving arequest signal from the position detecting device.